From 19be0eaffa3ac7d8eb6784ad9bdbc7d67ed8e619 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu, 13 Oct 2016 13:07:36 -0700
Subject: mm: remove gup_flags FOLL_WRITE games from __get_user_pages()

This is an ancient bug that was actually attempted to be fixed once
(badly) by me eleven years ago in commit 4ceb5db9757a ("Fix
get_user_pages() race for write access") but that was then undone due to
problems on s390 by commit f33ea7f404e5 ("fix get_user_pages bug").

In the meantime, the s390 situation has long been fixed, and we can now
fix it by checking the pte_dirty() bit properly (and do it better).  The
s390 dirty bit was implemented in abf09bed3cce ("s390/mm: implement
software dirty bits") which made it into v3.9.  Earlier kernels will
have to look at the page state itself.

Also, the VM has become more scalable, and what used a purely
theoretical race back then has become easier to trigger.

To fix it, we introduce a new internal FOLL_COW flag to mark the "yes,
we already did a COW" rather than play racy games with FOLL_WRITE that
is very fundamental, and then use the pte dirty flag to validate that
the FOLL_COW flag is still valid.

Reported-and-tested-by: Phil "not Paul" Oester <kernel@linuxace.com>
Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Michal Hocko <mhocko@suse.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Nick Piggin <npiggin@gmail.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 include/linux/mm.h | 1 +
 1 file changed, 1 insertion(+)

(limited to 'include')

diff --git a/include/linux/mm.h b/include/linux/mm.h
index e9caec6a51e9..ed85879f47f5 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2232,6 +2232,7 @@ static inline struct page *follow_page(struct vm_area_struct *vma,
 #define FOLL_TRIED	0x800	/* a retry, previous pass started an IO */
 #define FOLL_MLOCK	0x1000	/* lock present pages */
 #define FOLL_REMOTE	0x2000	/* we are working on non-current tsk/mm */
+#define FOLL_COW	0x4000	/* internal GUP flag */
 
 typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr,
 			void *data);
-- 
cgit v1.2.3-70-g09d2


From d4944b0ecec0af882483fe44b66729316e575208 Mon Sep 17 00:00:00 2001
From: Lorenzo Stoakes <lstoakes@gmail.com>
Date: Thu, 13 Oct 2016 01:20:12 +0100
Subject: mm: remove write/force parameters from __get_user_pages_unlocked()

This removes the redundant 'write' and 'force' parameters from
__get_user_pages_unlocked() to make the use of FOLL_FORCE explicit in
callers as use of this flag can result in surprising behaviour (and
hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 include/linux/mm.h     |  3 +--
 mm/gup.c               | 17 +++++++++--------
 mm/nommu.c             | 12 +++++++++---
 mm/process_vm_access.c |  7 +++++--
 virt/kvm/async_pf.c    |  3 ++-
 virt/kvm/kvm_main.c    | 11 ++++++++---
 6 files changed, 34 insertions(+), 19 deletions(-)

(limited to 'include')

diff --git a/include/linux/mm.h b/include/linux/mm.h
index ed85879f47f5..bcdea1f4e98c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1285,8 +1285,7 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
 		    int write, int force, struct page **pages, int *locked);
 long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
 			       unsigned long start, unsigned long nr_pages,
-			       int write, int force, struct page **pages,
-			       unsigned int gup_flags);
+			       struct page **pages, unsigned int gup_flags);
 long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
 		    int write, int force, struct page **pages);
 int get_user_pages_fast(unsigned long start, int nr_pages, int write,
diff --git a/mm/gup.c b/mm/gup.c
index 720eb9385204..e997f545b059 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -875,17 +875,11 @@ EXPORT_SYMBOL(get_user_pages_locked);
  */
 __always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
 					       unsigned long start, unsigned long nr_pages,
-					       int write, int force, struct page **pages,
-					       unsigned int gup_flags)
+					       struct page **pages, unsigned int gup_flags)
 {
 	long ret;
 	int locked = 1;
 
-	if (write)
-		gup_flags |= FOLL_WRITE;
-	if (force)
-		gup_flags |= FOLL_FORCE;
-
 	down_read(&mm->mmap_sem);
 	ret = __get_user_pages_locked(tsk, mm, start, nr_pages, pages, NULL,
 				      &locked, false, gup_flags);
@@ -915,8 +909,15 @@ EXPORT_SYMBOL(__get_user_pages_unlocked);
 long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
 			     int write, int force, struct page **pages)
 {
+	unsigned int flags = FOLL_TOUCH;
+
+	if (write)
+		flags |= FOLL_WRITE;
+	if (force)
+		flags |= FOLL_FORCE;
+
 	return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
-					 write, force, pages, FOLL_TOUCH);
+					 pages, flags);
 }
 EXPORT_SYMBOL(get_user_pages_unlocked);
 
diff --git a/mm/nommu.c b/mm/nommu.c
index 95daf81a4855..925dcc1fa2f3 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -185,8 +185,7 @@ EXPORT_SYMBOL(get_user_pages_locked);
 
 long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
 			       unsigned long start, unsigned long nr_pages,
-			       int write, int force, struct page **pages,
-			       unsigned int gup_flags)
+			       struct page **pages, unsigned int gup_flags)
 {
 	long ret;
 	down_read(&mm->mmap_sem);
@@ -200,8 +199,15 @@ EXPORT_SYMBOL(__get_user_pages_unlocked);
 long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
 			     int write, int force, struct page **pages)
 {
+	unsigned int flags = 0;
+
+	if (write)
+		flags |= FOLL_WRITE;
+	if (force)
+		flags |= FOLL_FORCE;
+
 	return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
-					 write, force, pages, 0);
+					 pages, flags);
 }
 EXPORT_SYMBOL(get_user_pages_unlocked);
 
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index 07514d41ebcc..be8dc8d1edb9 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -88,12 +88,16 @@ static int process_vm_rw_single_vec(unsigned long addr,
 	ssize_t rc = 0;
 	unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
 		/ sizeof(struct pages *);
+	unsigned int flags = FOLL_REMOTE;
 
 	/* Work out address and page range required */
 	if (len == 0)
 		return 0;
 	nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
 
+	if (vm_write)
+		flags |= FOLL_WRITE;
+
 	while (!rc && nr_pages && iov_iter_count(iter)) {
 		int pages = min(nr_pages, max_pages_per_loop);
 		size_t bytes;
@@ -104,8 +108,7 @@ static int process_vm_rw_single_vec(unsigned long addr,
 		 * current/current->mm
 		 */
 		pages = __get_user_pages_unlocked(task, mm, pa, pages,
-						  vm_write, 0, process_pages,
-						  FOLL_REMOTE);
+						  process_pages, flags);
 		if (pages <= 0)
 			return -EFAULT;
 
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index db9668869f6f..8035cc1eb955 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -84,7 +84,8 @@ static void async_pf_execute(struct work_struct *work)
 	 * mm and might be done in another context, so we must
 	 * use FOLL_REMOTE.
 	 */
-	__get_user_pages_unlocked(NULL, mm, addr, 1, 1, 0, NULL, FOLL_REMOTE);
+	__get_user_pages_unlocked(NULL, mm, addr, 1, NULL,
+			FOLL_WRITE | FOLL_REMOTE);
 
 	kvm_async_page_present_sync(vcpu, apf);
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 81dfc73d3df3..28510e72618a 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1416,10 +1416,15 @@ static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
 		down_read(&current->mm->mmap_sem);
 		npages = get_user_page_nowait(addr, write_fault, page);
 		up_read(&current->mm->mmap_sem);
-	} else
+	} else {
+		unsigned int flags = FOLL_TOUCH | FOLL_HWPOISON;
+
+		if (write_fault)
+			flags |= FOLL_WRITE;
+
 		npages = __get_user_pages_unlocked(current, current->mm, addr, 1,
-						   write_fault, 0, page,
-						   FOLL_TOUCH|FOLL_HWPOISON);
+						   page, flags);
+	}
 	if (npages != 1)
 		return npages;
 
-- 
cgit v1.2.3-70-g09d2


From c164154f66f0c9b02673f07aa4f044f1d9c70274 Mon Sep 17 00:00:00 2001
From: Lorenzo Stoakes <lstoakes@gmail.com>
Date: Thu, 13 Oct 2016 01:20:13 +0100
Subject: mm: replace get_user_pages_unlocked() write/force parameters with
 gup_flags

This removes the 'write' and 'force' use from get_user_pages_unlocked()
and replaces them with 'gup_flags' to make the use of FOLL_FORCE
explicit in callers as use of this flag can result in surprising
behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 arch/mips/mm/gup.c                 |  2 +-
 arch/s390/mm/gup.c                 |  3 ++-
 arch/sh/mm/gup.c                   |  3 ++-
 arch/sparc/mm/gup.c                |  3 ++-
 arch/x86/mm/gup.c                  |  2 +-
 drivers/media/pci/ivtv/ivtv-udma.c |  4 ++--
 drivers/media/pci/ivtv/ivtv-yuv.c  |  5 +++--
 drivers/scsi/st.c                  |  5 ++---
 drivers/video/fbdev/pvr2fb.c       |  4 ++--
 include/linux/mm.h                 |  2 +-
 mm/gup.c                           | 14 ++++----------
 mm/nommu.c                         | 11 ++---------
 mm/util.c                          |  3 ++-
 net/ceph/pagevec.c                 |  2 +-
 14 files changed, 27 insertions(+), 36 deletions(-)

(limited to 'include')

diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c
index 42d124fb6474..d8c3c159289a 100644
--- a/arch/mips/mm/gup.c
+++ b/arch/mips/mm/gup.c
@@ -287,7 +287,7 @@ slow_irqon:
 	pages += nr;
 
 	ret = get_user_pages_unlocked(start, (end - start) >> PAGE_SHIFT,
-				      write, 0, pages);
+				      pages, write ? FOLL_WRITE : 0);
 
 	/* Have to be a bit careful with return values */
 	if (nr > 0) {
diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c
index adb0c34bf431..18d4107e10ee 100644
--- a/arch/s390/mm/gup.c
+++ b/arch/s390/mm/gup.c
@@ -266,7 +266,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	/* Try to get the remaining pages with get_user_pages */
 	start += nr << PAGE_SHIFT;
 	pages += nr;
-	ret = get_user_pages_unlocked(start, nr_pages - nr, write, 0, pages);
+	ret = get_user_pages_unlocked(start, nr_pages - nr, pages,
+				      write ? FOLL_WRITE : 0);
 	/* Have to be a bit careful with return values */
 	if (nr > 0)
 		ret = (ret < 0) ? nr : ret + nr;
diff --git a/arch/sh/mm/gup.c b/arch/sh/mm/gup.c
index 40fa6c8adc43..063c298ba56c 100644
--- a/arch/sh/mm/gup.c
+++ b/arch/sh/mm/gup.c
@@ -258,7 +258,8 @@ slow_irqon:
 		pages += nr;
 
 		ret = get_user_pages_unlocked(start,
-			(end - start) >> PAGE_SHIFT, write, 0, pages);
+			(end - start) >> PAGE_SHIFT, pages,
+			write ? FOLL_WRITE : 0);
 
 		/* Have to be a bit careful with return values */
 		if (nr > 0) {
diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c
index 4e06750a5d29..cd0e32bbcb1d 100644
--- a/arch/sparc/mm/gup.c
+++ b/arch/sparc/mm/gup.c
@@ -238,7 +238,8 @@ slow:
 		pages += nr;
 
 		ret = get_user_pages_unlocked(start,
-			(end - start) >> PAGE_SHIFT, write, 0, pages);
+			(end - start) >> PAGE_SHIFT, pages,
+			write ? FOLL_WRITE : 0);
 
 		/* Have to be a bit careful with return values */
 		if (nr > 0) {
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index b8b6a60b32cf..0d4fb3ebbbac 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -435,7 +435,7 @@ slow_irqon:
 
 		ret = get_user_pages_unlocked(start,
 					      (end - start) >> PAGE_SHIFT,
-					      write, 0, pages);
+					      pages, write ? FOLL_WRITE : 0);
 
 		/* Have to be a bit careful with return values */
 		if (nr > 0) {
diff --git a/drivers/media/pci/ivtv/ivtv-udma.c b/drivers/media/pci/ivtv/ivtv-udma.c
index 4769469fe842..2c9232ef7baa 100644
--- a/drivers/media/pci/ivtv/ivtv-udma.c
+++ b/drivers/media/pci/ivtv/ivtv-udma.c
@@ -124,8 +124,8 @@ int ivtv_udma_setup(struct ivtv *itv, unsigned long ivtv_dest_addr,
 	}
 
 	/* Get user pages for DMA Xfer */
-	err = get_user_pages_unlocked(user_dma.uaddr, user_dma.page_count, 0,
-			1, dma->map);
+	err = get_user_pages_unlocked(user_dma.uaddr, user_dma.page_count,
+			dma->map, FOLL_FORCE);
 
 	if (user_dma.page_count != err) {
 		IVTV_DEBUG_WARN("failed to map user pages, returned %d instead of %d\n",
diff --git a/drivers/media/pci/ivtv/ivtv-yuv.c b/drivers/media/pci/ivtv/ivtv-yuv.c
index b094054cda6e..f7299d3d8244 100644
--- a/drivers/media/pci/ivtv/ivtv-yuv.c
+++ b/drivers/media/pci/ivtv/ivtv-yuv.c
@@ -76,11 +76,12 @@ static int ivtv_yuv_prep_user_dma(struct ivtv *itv, struct ivtv_user_dma *dma,
 
 	/* Get user pages for DMA Xfer */
 	y_pages = get_user_pages_unlocked(y_dma.uaddr,
-			y_dma.page_count, 0, 1, &dma->map[0]);
+			y_dma.page_count, &dma->map[0], FOLL_FORCE);
 	uv_pages = 0; /* silence gcc. value is set and consumed only if: */
 	if (y_pages == y_dma.page_count) {
 		uv_pages = get_user_pages_unlocked(uv_dma.uaddr,
-				uv_dma.page_count, 0, 1, &dma->map[y_pages]);
+				uv_dma.page_count, &dma->map[y_pages],
+				FOLL_FORCE);
 	}
 
 	if (y_pages != y_dma.page_count || uv_pages != uv_dma.page_count) {
diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index 7af5226aa55b..618422ea3a41 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -4922,9 +4922,8 @@ static int sgl_map_user_pages(struct st_buffer *STbp,
 	res = get_user_pages_unlocked(
 		uaddr,
 		nr_pages,
-		rw == READ,
-		0, /* don't force */
-		pages);
+		pages,
+		rw == READ ? FOLL_WRITE : 0); /* don't force */
 
 	/* Errors and no page mapped should return here */
 	if (res < nr_pages)
diff --git a/drivers/video/fbdev/pvr2fb.c b/drivers/video/fbdev/pvr2fb.c
index 3b1ca4411073..a2564ab91e62 100644
--- a/drivers/video/fbdev/pvr2fb.c
+++ b/drivers/video/fbdev/pvr2fb.c
@@ -686,8 +686,8 @@ static ssize_t pvr2fb_write(struct fb_info *info, const char *buf,
 	if (!pages)
 		return -ENOMEM;
 
-	ret = get_user_pages_unlocked((unsigned long)buf, nr_pages, WRITE,
-			0, pages);
+	ret = get_user_pages_unlocked((unsigned long)buf, nr_pages, pages,
+			FOLL_WRITE);
 
 	if (ret < nr_pages) {
 		nr_pages = ret;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index bcdea1f4e98c..abd53f2eb74e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1287,7 +1287,7 @@ long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
 			       unsigned long start, unsigned long nr_pages,
 			       struct page **pages, unsigned int gup_flags);
 long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
-		    int write, int force, struct page **pages);
+		    struct page **pages, unsigned int gup_flags);
 int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 			struct page **pages);
 
diff --git a/mm/gup.c b/mm/gup.c
index e997f545b059..373d1ec006e4 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -907,17 +907,10 @@ EXPORT_SYMBOL(__get_user_pages_unlocked);
  * "force" parameter).
  */
 long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
-			     int write, int force, struct page **pages)
+			     struct page **pages, unsigned int gup_flags)
 {
-	unsigned int flags = FOLL_TOUCH;
-
-	if (write)
-		flags |= FOLL_WRITE;
-	if (force)
-		flags |= FOLL_FORCE;
-
 	return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
-					 pages, flags);
+					 pages, gup_flags | FOLL_TOUCH);
 }
 EXPORT_SYMBOL(get_user_pages_unlocked);
 
@@ -1535,7 +1528,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 		start += nr << PAGE_SHIFT;
 		pages += nr;
 
-		ret = get_user_pages_unlocked(start, nr_pages - nr, write, 0, pages);
+		ret = get_user_pages_unlocked(start, nr_pages - nr, pages,
+				write ? FOLL_WRITE : 0);
 
 		/* Have to be a bit careful with return values */
 		if (nr > 0) {
diff --git a/mm/nommu.c b/mm/nommu.c
index 925dcc1fa2f3..7e27add39f7e 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -197,17 +197,10 @@ long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
 EXPORT_SYMBOL(__get_user_pages_unlocked);
 
 long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
-			     int write, int force, struct page **pages)
+			     struct page **pages, unsigned int gup_flags)
 {
-	unsigned int flags = 0;
-
-	if (write)
-		flags |= FOLL_WRITE;
-	if (force)
-		flags |= FOLL_FORCE;
-
 	return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
-					 pages, flags);
+					 pages, gup_flags);
 }
 EXPORT_SYMBOL(get_user_pages_unlocked);
 
diff --git a/mm/util.c b/mm/util.c
index 662cddf914af..4c685bde5ebc 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -283,7 +283,8 @@ EXPORT_SYMBOL_GPL(__get_user_pages_fast);
 int __weak get_user_pages_fast(unsigned long start,
 				int nr_pages, int write, struct page **pages)
 {
-	return get_user_pages_unlocked(start, nr_pages, write, 0, pages);
+	return get_user_pages_unlocked(start, nr_pages, pages,
+				       write ? FOLL_WRITE : 0);
 }
 EXPORT_SYMBOL_GPL(get_user_pages_fast);
 
diff --git a/net/ceph/pagevec.c b/net/ceph/pagevec.c
index 00d2601407c5..1a7c9a79a53c 100644
--- a/net/ceph/pagevec.c
+++ b/net/ceph/pagevec.c
@@ -26,7 +26,7 @@ struct page **ceph_get_direct_page_vector(const void __user *data,
 	while (got < num_pages) {
 		rc = get_user_pages_unlocked(
 		    (unsigned long)data + ((unsigned long)got * PAGE_SIZE),
-		    num_pages - got, write_page, 0, pages + got);
+		    num_pages - got, pages + got, write_page ? FOLL_WRITE : 0);
 		if (rc < 0)
 			break;
 		BUG_ON(rc == 0);
-- 
cgit v1.2.3-70-g09d2


From 3b913179c3fa89dd0e304193fa0c746fc0481447 Mon Sep 17 00:00:00 2001
From: Lorenzo Stoakes <lstoakes@gmail.com>
Date: Thu, 13 Oct 2016 01:20:14 +0100
Subject: mm: replace get_user_pages_locked() write/force parameters with
 gup_flags

This removes the 'write' and 'force' use from get_user_pages_locked()
and replaces them with 'gup_flags' to make the use of FOLL_FORCE
explicit in callers as use of this flag can result in surprising
behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 include/linux/mm.h |  2 +-
 mm/frame_vector.c  |  8 +++++++-
 mm/gup.c           | 12 +++---------
 mm/nommu.c         |  5 ++++-
 4 files changed, 15 insertions(+), 12 deletions(-)

(limited to 'include')

diff --git a/include/linux/mm.h b/include/linux/mm.h
index abd53f2eb74e..9fe9b0438169 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1282,7 +1282,7 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 			    int write, int force, struct page **pages,
 			    struct vm_area_struct **vmas);
 long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
-		    int write, int force, struct page **pages, int *locked);
+		    unsigned int gup_flags, struct page **pages, int *locked);
 long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
 			       unsigned long start, unsigned long nr_pages,
 			       struct page **pages, unsigned int gup_flags);
diff --git a/mm/frame_vector.c b/mm/frame_vector.c
index 381bb07ed14f..81b67498bb9c 100644
--- a/mm/frame_vector.c
+++ b/mm/frame_vector.c
@@ -41,10 +41,16 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
 	int ret = 0;
 	int err;
 	int locked;
+	unsigned int gup_flags = 0;
 
 	if (nr_frames == 0)
 		return 0;
 
+	if (write)
+		gup_flags |= FOLL_WRITE;
+	if (force)
+		gup_flags |= FOLL_FORCE;
+
 	if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
 		nr_frames = vec->nr_allocated;
 
@@ -59,7 +65,7 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
 		vec->got_ref = true;
 		vec->is_pfns = false;
 		ret = get_user_pages_locked(start, nr_frames,
-			write, force, (struct page **)(vec->ptrs), &locked);
+			gup_flags, (struct page **)(vec->ptrs), &locked);
 		goto out;
 	}
 
diff --git a/mm/gup.c b/mm/gup.c
index 373d1ec006e4..3cfb55ef0cf4 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -848,18 +848,12 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
  *          up_read(&mm->mmap_sem);
  */
 long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
-			   int write, int force, struct page **pages,
+			   unsigned int gup_flags, struct page **pages,
 			   int *locked)
 {
-	unsigned int flags = FOLL_TOUCH;
-
-	if (write)
-		flags |= FOLL_WRITE;
-	if (force)
-		flags |= FOLL_FORCE;
-
 	return __get_user_pages_locked(current, current->mm, start, nr_pages,
-				       pages, NULL, locked, true, flags);
+				       pages, NULL, locked, true,
+				       gup_flags | FOLL_TOUCH);
 }
 EXPORT_SYMBOL(get_user_pages_locked);
 
diff --git a/mm/nommu.c b/mm/nommu.c
index 7e27add39f7e..842cfdd1a31e 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -176,9 +176,12 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
 EXPORT_SYMBOL(get_user_pages);
 
 long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
-			    int write, int force, struct page **pages,
+			    unsigned int gup_flags, struct page **pages,
 			    int *locked)
 {
+	int write = gup_flags & FOLL_WRITE;
+	int force = gup_flags & FOLL_FORCE;
+
 	return get_user_pages(start, nr_pages, write, force, pages, NULL);
 }
 EXPORT_SYMBOL(get_user_pages_locked);
-- 
cgit v1.2.3-70-g09d2


From 7f23b3504a0df63b724180262c5f3f117f21bcae Mon Sep 17 00:00:00 2001
From: Lorenzo Stoakes <lstoakes@gmail.com>
Date: Thu, 13 Oct 2016 01:20:15 +0100
Subject: mm: replace get_vaddr_frames() write/force parameters with gup_flags

This removes the 'write' and 'force' from get_vaddr_frames() and
replaces them with 'gup_flags' to make the use of FOLL_FORCE explicit in
callers as use of this flag can result in surprising behaviour (and
hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 drivers/gpu/drm/exynos/exynos_drm_g2d.c    |  3 ++-
 drivers/media/platform/omap/omap_vout.c    |  2 +-
 drivers/media/v4l2-core/videobuf2-memops.c |  6 +++++-
 include/linux/mm.h                         |  2 +-
 mm/frame_vector.c                          | 13 ++-----------
 5 files changed, 11 insertions(+), 15 deletions(-)

(limited to 'include')

diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
index aa92decf4233..fbd13fabdf2d 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
@@ -488,7 +488,8 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct drm_device *drm_dev,
 		goto err_free;
 	}
 
-	ret = get_vaddr_frames(start, npages, true, true, g2d_userptr->vec);
+	ret = get_vaddr_frames(start, npages, FOLL_FORCE | FOLL_WRITE,
+		g2d_userptr->vec);
 	if (ret != npages) {
 		DRM_ERROR("failed to get user pages from userptr.\n");
 		if (ret < 0)
diff --git a/drivers/media/platform/omap/omap_vout.c b/drivers/media/platform/omap/omap_vout.c
index e668dde6d857..a31b95cb3b09 100644
--- a/drivers/media/platform/omap/omap_vout.c
+++ b/drivers/media/platform/omap/omap_vout.c
@@ -214,7 +214,7 @@ static int omap_vout_get_userptr(struct videobuf_buffer *vb, u32 virtp,
 	if (!vec)
 		return -ENOMEM;
 
-	ret = get_vaddr_frames(virtp, 1, true, false, vec);
+	ret = get_vaddr_frames(virtp, 1, FOLL_WRITE, vec);
 	if (ret != 1) {
 		frame_vector_destroy(vec);
 		return -EINVAL;
diff --git a/drivers/media/v4l2-core/videobuf2-memops.c b/drivers/media/v4l2-core/videobuf2-memops.c
index 3c3b517f1d1c..1cd322e939c7 100644
--- a/drivers/media/v4l2-core/videobuf2-memops.c
+++ b/drivers/media/v4l2-core/videobuf2-memops.c
@@ -42,6 +42,10 @@ struct frame_vector *vb2_create_framevec(unsigned long start,
 	unsigned long first, last;
 	unsigned long nr;
 	struct frame_vector *vec;
+	unsigned int flags = FOLL_FORCE;
+
+	if (write)
+		flags |= FOLL_WRITE;
 
 	first = start >> PAGE_SHIFT;
 	last = (start + length - 1) >> PAGE_SHIFT;
@@ -49,7 +53,7 @@ struct frame_vector *vb2_create_framevec(unsigned long start,
 	vec = frame_vector_create(nr);
 	if (!vec)
 		return ERR_PTR(-ENOMEM);
-	ret = get_vaddr_frames(start & PAGE_MASK, nr, write, true, vec);
+	ret = get_vaddr_frames(start & PAGE_MASK, nr, flags, vec);
 	if (ret < 0)
 		goto out_destroy;
 	/* We accept only complete set of PFNs */
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9fe9b0438169..91cc923ce985 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1305,7 +1305,7 @@ struct frame_vector {
 struct frame_vector *frame_vector_create(unsigned int nr_frames);
 void frame_vector_destroy(struct frame_vector *vec);
 int get_vaddr_frames(unsigned long start, unsigned int nr_pfns,
-		     bool write, bool force, struct frame_vector *vec);
+		     unsigned int gup_flags, struct frame_vector *vec);
 void put_vaddr_frames(struct frame_vector *vec);
 int frame_vector_to_pages(struct frame_vector *vec);
 void frame_vector_to_pfns(struct frame_vector *vec);
diff --git a/mm/frame_vector.c b/mm/frame_vector.c
index 81b67498bb9c..db77dcb38afd 100644
--- a/mm/frame_vector.c
+++ b/mm/frame_vector.c
@@ -11,10 +11,7 @@
  * get_vaddr_frames() - map virtual addresses to pfns
  * @start:	starting user address
  * @nr_frames:	number of pages / pfns from start to map
- * @write:	whether pages will be written to by the caller
- * @force:	whether to force write access even if user mapping is
- *		readonly. See description of the same argument of
-		get_user_pages().
+ * @gup_flags:	flags modifying lookup behaviour
  * @vec:	structure which receives pages / pfns of the addresses mapped.
  *		It should have space for at least nr_frames entries.
  *
@@ -34,23 +31,17 @@
  * This function takes care of grabbing mmap_sem as necessary.
  */
 int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
-		     bool write, bool force, struct frame_vector *vec)
+		     unsigned int gup_flags, struct frame_vector *vec)
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
 	int ret = 0;
 	int err;
 	int locked;
-	unsigned int gup_flags = 0;
 
 	if (nr_frames == 0)
 		return 0;
 
-	if (write)
-		gup_flags |= FOLL_WRITE;
-	if (force)
-		gup_flags |= FOLL_FORCE;
-
 	if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
 		nr_frames = vec->nr_allocated;
 
-- 
cgit v1.2.3-70-g09d2


From 768ae309a96103ed02eb1e111e838c87854d8b51 Mon Sep 17 00:00:00 2001
From: Lorenzo Stoakes <lstoakes@gmail.com>
Date: Thu, 13 Oct 2016 01:20:16 +0100
Subject: mm: replace get_user_pages() write/force parameters with gup_flags
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This removes the 'write' and 'force' from get_user_pages() and replaces
them with 'gup_flags' to make the use of FOLL_FORCE explicit in callers
as use of this flag can result in surprising behaviour (and hence bugs)
within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 arch/cris/arch-v32/drivers/cryptocop.c                 |  4 +---
 arch/ia64/kernel/err_inject.c                          |  2 +-
 arch/x86/mm/mpx.c                                      |  5 ++---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c                |  7 +++++--
 drivers/gpu/drm/radeon/radeon_ttm.c                    |  3 ++-
 drivers/gpu/drm/via/via_dmablit.c                      |  4 ++--
 drivers/infiniband/core/umem.c                         |  6 +++++-
 drivers/infiniband/hw/mthca/mthca_memfree.c            |  2 +-
 drivers/infiniband/hw/qib/qib_user_pages.c             |  3 ++-
 drivers/infiniband/hw/usnic/usnic_uiom.c               |  5 ++++-
 drivers/media/v4l2-core/videobuf-dma-sg.c              |  7 +++++--
 drivers/misc/mic/scif/scif_rma.c                       |  3 +--
 drivers/misc/sgi-gru/grufault.c                        |  2 +-
 drivers/platform/goldfish/goldfish_pipe.c              |  3 ++-
 drivers/rapidio/devices/rio_mport_cdev.c               |  3 ++-
 .../vc04_services/interface/vchiq_arm/vchiq_2835_arm.c |  3 +--
 .../vc04_services/interface/vchiq_arm/vchiq_arm.c      |  3 +--
 drivers/virt/fsl_hypervisor.c                          |  4 ++--
 include/linux/mm.h                                     |  2 +-
 mm/gup.c                                               | 12 +++---------
 mm/mempolicy.c                                         |  2 +-
 mm/nommu.c                                             | 18 ++++--------------
 22 files changed, 49 insertions(+), 54 deletions(-)

(limited to 'include')

diff --git a/arch/cris/arch-v32/drivers/cryptocop.c b/arch/cris/arch-v32/drivers/cryptocop.c
index b5698c876fcc..099e170a93ee 100644
--- a/arch/cris/arch-v32/drivers/cryptocop.c
+++ b/arch/cris/arch-v32/drivers/cryptocop.c
@@ -2722,7 +2722,6 @@ static int cryptocop_ioctl_process(struct inode *inode, struct file *filp, unsig
 	err = get_user_pages((unsigned long int)(oper.indata + prev_ix),
 			     noinpages,
 			     0,  /* read access only for in data */
-			     0, /* no force */
 			     inpages,
 			     NULL);
 
@@ -2736,8 +2735,7 @@ static int cryptocop_ioctl_process(struct inode *inode, struct file *filp, unsig
 	if (oper.do_cipher){
 		err = get_user_pages((unsigned long int)oper.cipher_outdata,
 				     nooutpages,
-				     1, /* write access for out data */
-				     0, /* no force */
+				     FOLL_WRITE, /* write access for out data */
 				     outpages,
 				     NULL);
 		up_read(&current->mm->mmap_sem);
diff --git a/arch/ia64/kernel/err_inject.c b/arch/ia64/kernel/err_inject.c
index 09f845793d12..5ed0ea92c5bf 100644
--- a/arch/ia64/kernel/err_inject.c
+++ b/arch/ia64/kernel/err_inject.c
@@ -142,7 +142,7 @@ store_virtual_to_phys(struct device *dev, struct device_attribute *attr,
 	u64 virt_addr=simple_strtoull(buf, NULL, 16);
 	int ret;
 
-	ret = get_user_pages(virt_addr, 1, VM_READ, 0, NULL, NULL);
+	ret = get_user_pages(virt_addr, 1, FOLL_WRITE, NULL, NULL);
 	if (ret<=0) {
 #ifdef ERR_INJ_DEBUG
 		printk("Virtual address %lx is not existing.\n",virt_addr);
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 80476878eb4c..e4f800999b32 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -544,10 +544,9 @@ static int mpx_resolve_fault(long __user *addr, int write)
 {
 	long gup_ret;
 	int nr_pages = 1;
-	int force = 0;
 
-	gup_ret = get_user_pages((unsigned long)addr, nr_pages, write,
-			force, NULL, NULL);
+	gup_ret = get_user_pages((unsigned long)addr, nr_pages,
+			write ? FOLL_WRITE : 0,	NULL, NULL);
 	/*
 	 * get_user_pages() returns number of pages gotten.
 	 * 0 means we failed to fault in and get anything,
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 887483b8b818..dcaf691f56b5 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -555,10 +555,13 @@ struct amdgpu_ttm_tt {
 int amdgpu_ttm_tt_get_user_pages(struct ttm_tt *ttm, struct page **pages)
 {
 	struct amdgpu_ttm_tt *gtt = (void *)ttm;
-	int write = !(gtt->userflags & AMDGPU_GEM_USERPTR_READONLY);
+	unsigned int flags = 0;
 	unsigned pinned = 0;
 	int r;
 
+	if (!(gtt->userflags & AMDGPU_GEM_USERPTR_READONLY))
+		flags |= FOLL_WRITE;
+
 	if (gtt->userflags & AMDGPU_GEM_USERPTR_ANONONLY) {
 		/* check that we only use anonymous memory
 		   to prevent problems with writeback */
@@ -581,7 +584,7 @@ int amdgpu_ttm_tt_get_user_pages(struct ttm_tt *ttm, struct page **pages)
 		list_add(&guptask.list, &gtt->guptasks);
 		spin_unlock(&gtt->guptasklock);
 
-		r = get_user_pages(userptr, num_pages, write, 0, p, NULL);
+		r = get_user_pages(userptr, num_pages, flags, p, NULL);
 
 		spin_lock(&gtt->guptasklock);
 		list_del(&guptask.list);
diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
index 455268214b89..3de5e6e21662 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -566,7 +566,8 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt *ttm)
 		uint64_t userptr = gtt->userptr + pinned * PAGE_SIZE;
 		struct page **pages = ttm->pages + pinned;
 
-		r = get_user_pages(userptr, num_pages, write, 0, pages, NULL);
+		r = get_user_pages(userptr, num_pages, write ? FOLL_WRITE : 0,
+				   pages, NULL);
 		if (r < 0)
 			goto release_pages;
 
diff --git a/drivers/gpu/drm/via/via_dmablit.c b/drivers/gpu/drm/via/via_dmablit.c
index 7e2a12c4fed2..1a3ad769f8c8 100644
--- a/drivers/gpu/drm/via/via_dmablit.c
+++ b/drivers/gpu/drm/via/via_dmablit.c
@@ -241,8 +241,8 @@ via_lock_all_dma_pages(drm_via_sg_info_t *vsg,  drm_via_dmablit_t *xfer)
 	down_read(&current->mm->mmap_sem);
 	ret = get_user_pages((unsigned long)xfer->mem_addr,
 			     vsg->num_pages,
-			     (vsg->direction == DMA_FROM_DEVICE),
-			     0, vsg->pages, NULL);
+			     (vsg->direction == DMA_FROM_DEVICE) ? FOLL_WRITE : 0,
+			     vsg->pages, NULL);
 
 	up_read(&current->mm->mmap_sem);
 	if (ret != vsg->num_pages) {
diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index c68746ce6624..224ad274ea0b 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -94,6 +94,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
 	unsigned long dma_attrs = 0;
 	struct scatterlist *sg, *sg_list_start;
 	int need_release = 0;
+	unsigned int gup_flags = FOLL_WRITE;
 
 	if (dmasync)
 		dma_attrs |= DMA_ATTR_WRITE_BARRIER;
@@ -183,6 +184,9 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
 	if (ret)
 		goto out;
 
+	if (!umem->writable)
+		gup_flags |= FOLL_FORCE;
+
 	need_release = 1;
 	sg_list_start = umem->sg_head.sgl;
 
@@ -190,7 +194,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
 		ret = get_user_pages(cur_base,
 				     min_t(unsigned long, npages,
 					   PAGE_SIZE / sizeof (struct page *)),
-				     1, !umem->writable, page_list, vma_list);
+				     gup_flags, page_list, vma_list);
 
 		if (ret < 0)
 			goto out;
diff --git a/drivers/infiniband/hw/mthca/mthca_memfree.c b/drivers/infiniband/hw/mthca/mthca_memfree.c
index 6c00d04b8b28..c6fe89d79248 100644
--- a/drivers/infiniband/hw/mthca/mthca_memfree.c
+++ b/drivers/infiniband/hw/mthca/mthca_memfree.c
@@ -472,7 +472,7 @@ int mthca_map_user_db(struct mthca_dev *dev, struct mthca_uar *uar,
 		goto out;
 	}
 
-	ret = get_user_pages(uaddr & PAGE_MASK, 1, 1, 0, pages, NULL);
+	ret = get_user_pages(uaddr & PAGE_MASK, 1, FOLL_WRITE, pages, NULL);
 	if (ret < 0)
 		goto out;
 
diff --git a/drivers/infiniband/hw/qib/qib_user_pages.c b/drivers/infiniband/hw/qib/qib_user_pages.c
index 2d2b94fd3633..75f08624ac05 100644
--- a/drivers/infiniband/hw/qib/qib_user_pages.c
+++ b/drivers/infiniband/hw/qib/qib_user_pages.c
@@ -67,7 +67,8 @@ static int __qib_get_user_pages(unsigned long start_page, size_t num_pages,
 
 	for (got = 0; got < num_pages; got += ret) {
 		ret = get_user_pages(start_page + got * PAGE_SIZE,
-				     num_pages - got, 1, 1,
+				     num_pages - got,
+				     FOLL_WRITE | FOLL_FORCE,
 				     p + got, NULL);
 		if (ret < 0)
 			goto bail_release;
diff --git a/drivers/infiniband/hw/usnic/usnic_uiom.c b/drivers/infiniband/hw/usnic/usnic_uiom.c
index a0b6ebee4d8a..1ccee6ea5bc3 100644
--- a/drivers/infiniband/hw/usnic/usnic_uiom.c
+++ b/drivers/infiniband/hw/usnic/usnic_uiom.c
@@ -111,6 +111,7 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
 	int i;
 	int flags;
 	dma_addr_t pa;
+	unsigned int gup_flags;
 
 	if (!can_do_mlock())
 		return -EPERM;
@@ -135,6 +136,8 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
 
 	flags = IOMMU_READ | IOMMU_CACHE;
 	flags |= (writable) ? IOMMU_WRITE : 0;
+	gup_flags = FOLL_WRITE;
+	gup_flags |= (writable) ? 0 : FOLL_FORCE;
 	cur_base = addr & PAGE_MASK;
 	ret = 0;
 
@@ -142,7 +145,7 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
 		ret = get_user_pages(cur_base,
 					min_t(unsigned long, npages,
 					PAGE_SIZE / sizeof(struct page *)),
-					1, !writable, page_list, NULL);
+					gup_flags, page_list, NULL);
 
 		if (ret < 0)
 			goto out;
diff --git a/drivers/media/v4l2-core/videobuf-dma-sg.c b/drivers/media/v4l2-core/videobuf-dma-sg.c
index f300f060b3f3..1db0af6c7f94 100644
--- a/drivers/media/v4l2-core/videobuf-dma-sg.c
+++ b/drivers/media/v4l2-core/videobuf-dma-sg.c
@@ -156,6 +156,7 @@ static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
 {
 	unsigned long first, last;
 	int err, rw = 0;
+	unsigned int flags = FOLL_FORCE;
 
 	dma->direction = direction;
 	switch (dma->direction) {
@@ -178,12 +179,14 @@ static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
 	if (NULL == dma->pages)
 		return -ENOMEM;
 
+	if (rw == READ)
+		flags |= FOLL_WRITE;
+
 	dprintk(1, "init user [0x%lx+0x%lx => %d pages]\n",
 		data, size, dma->nr_pages);
 
 	err = get_user_pages(data & PAGE_MASK, dma->nr_pages,
-			     rw == READ, 1, /* force */
-			     dma->pages, NULL);
+			     flags, dma->pages, NULL);
 
 	if (err != dma->nr_pages) {
 		dma->nr_pages = (err >= 0) ? err : 0;
diff --git a/drivers/misc/mic/scif/scif_rma.c b/drivers/misc/mic/scif/scif_rma.c
index e0203b1a20fd..f806a4471eb9 100644
--- a/drivers/misc/mic/scif/scif_rma.c
+++ b/drivers/misc/mic/scif/scif_rma.c
@@ -1396,8 +1396,7 @@ retry:
 		pinned_pages->nr_pages = get_user_pages(
 				(u64)addr,
 				nr_pages,
-				!!(prot & SCIF_PROT_WRITE),
-				0,
+				(prot & SCIF_PROT_WRITE) ? FOLL_WRITE : 0,
 				pinned_pages->pages,
 				NULL);
 		up_write(&mm->mmap_sem);
diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c
index a2d97b9b17e3..6fb773dbcd0c 100644
--- a/drivers/misc/sgi-gru/grufault.c
+++ b/drivers/misc/sgi-gru/grufault.c
@@ -198,7 +198,7 @@ static int non_atomic_pte_lookup(struct vm_area_struct *vma,
 #else
 	*pageshift = PAGE_SHIFT;
 #endif
-	if (get_user_pages(vaddr, 1, write, 0, &page, NULL) <= 0)
+	if (get_user_pages(vaddr, 1, write ? FOLL_WRITE : 0, &page, NULL) <= 0)
 		return -EFAULT;
 	*paddr = page_to_phys(page);
 	put_page(page);
diff --git a/drivers/platform/goldfish/goldfish_pipe.c b/drivers/platform/goldfish/goldfish_pipe.c
index 07462d79d040..1aba2c74160e 100644
--- a/drivers/platform/goldfish/goldfish_pipe.c
+++ b/drivers/platform/goldfish/goldfish_pipe.c
@@ -309,7 +309,8 @@ static ssize_t goldfish_pipe_read_write(struct file *filp, char __user *buffer,
 		 * much memory to the process.
 		 */
 		down_read(&current->mm->mmap_sem);
-		ret = get_user_pages(address, 1, !is_write, 0, &page, NULL);
+		ret = get_user_pages(address, 1, is_write ? 0 : FOLL_WRITE,
+				&page, NULL);
 		up_read(&current->mm->mmap_sem);
 		if (ret < 0)
 			break;
diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c
index 436dfe871d32..9013a585507e 100644
--- a/drivers/rapidio/devices/rio_mport_cdev.c
+++ b/drivers/rapidio/devices/rio_mport_cdev.c
@@ -892,7 +892,8 @@ rio_dma_transfer(struct file *filp, u32 transfer_mode,
 		down_read(&current->mm->mmap_sem);
 		pinned = get_user_pages(
 				(unsigned long)xfer->loc_addr & PAGE_MASK,
-				nr_pages, dir == DMA_FROM_DEVICE, 0,
+				nr_pages,
+				dir == DMA_FROM_DEVICE ? FOLL_WRITE : 0,
 				page_list, NULL);
 		up_read(&current->mm->mmap_sem);
 
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
index c29040fdf9a7..1091b9f1dd07 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
@@ -423,8 +423,7 @@ create_pagelist(char __user *buf, size_t count, unsigned short type,
 		actual_pages = get_user_pages(task, task->mm,
 				          (unsigned long)buf & ~(PAGE_SIZE - 1),
 					  num_pages,
-					  (type == PAGELIST_READ) /*Write */ ,
-					  0 /*Force */ ,
+					  (type == PAGELIST_READ) ? FOLL_WRITE : 0,
 					  pages,
 					  NULL /*vmas */);
 		up_read(&task->mm->mmap_sem);
diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
index e11c0e07471b..7b6cd4d80621 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
@@ -1477,8 +1477,7 @@ dump_phys_mem(void *virt_addr, uint32_t num_bytes)
 		current->mm,              /* mm */
 		(unsigned long)virt_addr, /* start */
 		num_pages,                /* len */
-		0,                        /* write */
-		0,                        /* force */
+		0,                        /* gup_flags */
 		pages,                    /* pages (array of page pointers) */
 		NULL);                    /* vmas */
 	up_read(&current->mm->mmap_sem);
diff --git a/drivers/virt/fsl_hypervisor.c b/drivers/virt/fsl_hypervisor.c
index 60bdad3a689b..150ce2abf6c8 100644
--- a/drivers/virt/fsl_hypervisor.c
+++ b/drivers/virt/fsl_hypervisor.c
@@ -245,8 +245,8 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
 	/* Get the physical addresses of the source buffer */
 	down_read(&current->mm->mmap_sem);
 	num_pinned = get_user_pages(param.local_vaddr - lb_offset,
-		num_pages, (param.source == -1) ? READ : WRITE,
-		0, pages, NULL);
+		num_pages, (param.source == -1) ? 0 : FOLL_WRITE,
+		pages, NULL);
 	up_read(&current->mm->mmap_sem);
 
 	if (num_pinned != num_pages) {
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 91cc923ce985..30bb5d9631bb 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1279,7 +1279,7 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
 			    int write, int force, struct page **pages,
 			    struct vm_area_struct **vmas);
 long get_user_pages(unsigned long start, unsigned long nr_pages,
-			    int write, int force, struct page **pages,
+			    unsigned int gup_flags, struct page **pages,
 			    struct vm_area_struct **vmas);
 long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
 		    unsigned int gup_flags, struct page **pages, int *locked);
diff --git a/mm/gup.c b/mm/gup.c
index 3cfb55ef0cf4..bbc2e76cdd77 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -987,18 +987,12 @@ EXPORT_SYMBOL(get_user_pages_remote);
  * obviously don't pass FOLL_REMOTE in here.
  */
 long get_user_pages(unsigned long start, unsigned long nr_pages,
-		int write, int force, struct page **pages,
+		unsigned int gup_flags, struct page **pages,
 		struct vm_area_struct **vmas)
 {
-	unsigned int flags = FOLL_TOUCH;
-
-	if (write)
-		flags |= FOLL_WRITE;
-	if (force)
-		flags |= FOLL_FORCE;
-
 	return __get_user_pages_locked(current, current->mm, start, nr_pages,
-				       pages, vmas, NULL, false, flags);
+				       pages, vmas, NULL, false,
+				       gup_flags | FOLL_TOUCH);
 }
 EXPORT_SYMBOL(get_user_pages);
 
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index ad1c96ac313c..0b859af06b87 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -850,7 +850,7 @@ static int lookup_node(unsigned long addr)
 	struct page *p;
 	int err;
 
-	err = get_user_pages(addr & PAGE_MASK, 1, 0, 0, &p, NULL);
+	err = get_user_pages(addr & PAGE_MASK, 1, 0, &p, NULL);
 	if (err >= 0) {
 		err = page_to_nid(p);
 		put_page(p);
diff --git a/mm/nommu.c b/mm/nommu.c
index 842cfdd1a31e..70cb844dfd95 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -160,18 +160,11 @@ finish_or_fault:
  * - don't permit access to VMAs that don't support it, such as I/O mappings
  */
 long get_user_pages(unsigned long start, unsigned long nr_pages,
-		    int write, int force, struct page **pages,
+		    unsigned int gup_flags, struct page **pages,
 		    struct vm_area_struct **vmas)
 {
-	int flags = 0;
-
-	if (write)
-		flags |= FOLL_WRITE;
-	if (force)
-		flags |= FOLL_FORCE;
-
-	return __get_user_pages(current, current->mm, start, nr_pages, flags,
-				pages, vmas, NULL);
+	return __get_user_pages(current, current->mm, start, nr_pages,
+				gup_flags, pages, vmas, NULL);
 }
 EXPORT_SYMBOL(get_user_pages);
 
@@ -179,10 +172,7 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
 			    unsigned int gup_flags, struct page **pages,
 			    int *locked)
 {
-	int write = gup_flags & FOLL_WRITE;
-	int force = gup_flags & FOLL_FORCE;
-
-	return get_user_pages(start, nr_pages, write, force, pages, NULL);
+	return get_user_pages(start, nr_pages, gup_flags, pages, NULL);
 }
 EXPORT_SYMBOL(get_user_pages_locked);
 
-- 
cgit v1.2.3-70-g09d2


From 9beae1ea89305a9667ceaab6d0bf46a045ad71e7 Mon Sep 17 00:00:00 2001
From: Lorenzo Stoakes <lstoakes@gmail.com>
Date: Thu, 13 Oct 2016 01:20:17 +0100
Subject: mm: replace get_user_pages_remote() write/force parameters with
 gup_flags

This removes the 'write' and 'force' from get_user_pages_remote() and
replaces them with 'gup_flags' to make the use of FOLL_FORCE explicit in
callers as use of this flag can result in surprising behaviour (and
hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 drivers/gpu/drm/etnaviv/etnaviv_gem.c   |  7 +++++--
 drivers/gpu/drm/i915/i915_gem_userptr.c |  6 +++++-
 drivers/infiniband/core/umem_odp.c      |  7 +++++--
 fs/exec.c                               |  9 +++++++--
 include/linux/mm.h                      |  2 +-
 kernel/events/uprobes.c                 |  6 ++++--
 mm/gup.c                                | 22 +++++++---------------
 mm/memory.c                             |  6 +++++-
 security/tomoyo/domain.c                |  2 +-
 9 files changed, 40 insertions(+), 27 deletions(-)

(limited to 'include')

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index 5ce3603e6eac..0370b842d9cc 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -748,19 +748,22 @@ static struct page **etnaviv_gem_userptr_do_get_pages(
 	int ret = 0, pinned, npages = etnaviv_obj->base.size >> PAGE_SHIFT;
 	struct page **pvec;
 	uintptr_t ptr;
+	unsigned int flags = 0;
 
 	pvec = drm_malloc_ab(npages, sizeof(struct page *));
 	if (!pvec)
 		return ERR_PTR(-ENOMEM);
 
+	if (!etnaviv_obj->userptr.ro)
+		flags |= FOLL_WRITE;
+
 	pinned = 0;
 	ptr = etnaviv_obj->userptr.ptr;
 
 	down_read(&mm->mmap_sem);
 	while (pinned < npages) {
 		ret = get_user_pages_remote(task, mm, ptr, npages - pinned,
-					    !etnaviv_obj->userptr.ro, 0,
-					    pvec + pinned, NULL);
+					    flags, pvec + pinned, NULL);
 		if (ret < 0)
 			break;
 
diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index e537930c64b5..c6f780f5abc9 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -508,6 +508,10 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
 	pvec = drm_malloc_gfp(npages, sizeof(struct page *), GFP_TEMPORARY);
 	if (pvec != NULL) {
 		struct mm_struct *mm = obj->userptr.mm->mm;
+		unsigned int flags = 0;
+
+		if (!obj->userptr.read_only)
+			flags |= FOLL_WRITE;
 
 		ret = -EFAULT;
 		if (atomic_inc_not_zero(&mm->mm_users)) {
@@ -517,7 +521,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
 					(work->task, mm,
 					 obj->userptr.ptr + pinned * PAGE_SIZE,
 					 npages - pinned,
-					 !obj->userptr.read_only, 0,
+					 flags,
 					 pvec + pinned, NULL);
 				if (ret < 0)
 					break;
diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index 75077a018675..1f0fe3217f23 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -527,6 +527,7 @@ int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt,
 	u64 off;
 	int j, k, ret = 0, start_idx, npages = 0;
 	u64 base_virt_addr;
+	unsigned int flags = 0;
 
 	if (access_mask == 0)
 		return -EINVAL;
@@ -556,6 +557,9 @@ int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt,
 		goto out_put_task;
 	}
 
+	if (access_mask & ODP_WRITE_ALLOWED_BIT)
+		flags |= FOLL_WRITE;
+
 	start_idx = (user_virt - ib_umem_start(umem)) >> PAGE_SHIFT;
 	k = start_idx;
 
@@ -574,8 +578,7 @@ int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 user_virt, u64 bcnt,
 		 */
 		npages = get_user_pages_remote(owning_process, owning_mm,
 				user_virt, gup_num_pages,
-				access_mask & ODP_WRITE_ALLOWED_BIT,
-				0, local_page_list, NULL);
+				flags, local_page_list, NULL);
 		up_read(&owning_mm->mmap_sem);
 
 		if (npages < 0)
diff --git a/fs/exec.c b/fs/exec.c
index 6fcfb3f7b137..4e497b9ee71e 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -191,6 +191,7 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 {
 	struct page *page;
 	int ret;
+	unsigned int gup_flags = FOLL_FORCE;
 
 #ifdef CONFIG_STACK_GROWSUP
 	if (write) {
@@ -199,12 +200,16 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
 			return NULL;
 	}
 #endif
+
+	if (write)
+		gup_flags |= FOLL_WRITE;
+
 	/*
 	 * We are doing an exec().  'current' is the process
 	 * doing the exec and bprm->mm is the new process's mm.
 	 */
-	ret = get_user_pages_remote(current, bprm->mm, pos, 1, write,
-			1, &page, NULL);
+	ret = get_user_pages_remote(current, bprm->mm, pos, 1, gup_flags,
+			&page, NULL);
 	if (ret <= 0)
 		return NULL;
 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 30bb5d9631bb..ecc4be7b67e0 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1276,7 +1276,7 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 		      struct vm_area_struct **vmas, int *nonblocking);
 long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
 			    unsigned long start, unsigned long nr_pages,
-			    int write, int force, struct page **pages,
+			    unsigned int gup_flags, struct page **pages,
 			    struct vm_area_struct **vmas);
 long get_user_pages(unsigned long start, unsigned long nr_pages,
 			    unsigned int gup_flags, struct page **pages,
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index d4129bb05e5d..f9ec9add2164 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -300,7 +300,8 @@ int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr,
 
 retry:
 	/* Read the page with vaddr into memory */
-	ret = get_user_pages_remote(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma);
+	ret = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &old_page,
+			&vma);
 	if (ret <= 0)
 		return ret;
 
@@ -1710,7 +1711,8 @@ static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr)
 	 * but we treat this as a 'remote' access since it is
 	 * essentially a kernel access to the memory.
 	 */
-	result = get_user_pages_remote(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
+	result = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &page,
+			NULL);
 	if (result < 0)
 		return result;
 
diff --git a/mm/gup.c b/mm/gup.c
index bbc2e76cdd77..7aa113c2d373 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -915,9 +915,7 @@ EXPORT_SYMBOL(get_user_pages_unlocked);
  * @mm:		mm_struct of target mm
  * @start:	starting user address
  * @nr_pages:	number of pages from start to pin
- * @write:	whether pages will be written to by the caller
- * @force:	whether to force access even when user mapping is currently
- *		protected (but never forces write access to shared mapping).
+ * @gup_flags:	flags modifying lookup behaviour
  * @pages:	array that receives pointers to the pages pinned.
  *		Should be at least nr_pages long. Or NULL, if caller
  *		only intends to ensure the pages are faulted in.
@@ -946,9 +944,9 @@ EXPORT_SYMBOL(get_user_pages_unlocked);
  * or similar operation cannot guarantee anything stronger anyway because
  * locks can't be held over the syscall boundary.
  *
- * If write=0, the page must not be written to. If the page is written to,
- * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
- * after the page is finished with, and before put_page is called.
+ * If gup_flags & FOLL_WRITE == 0, the page must not be written to. If the page
+ * is written to, set_page_dirty (or set_page_dirty_lock, as appropriate) must
+ * be called after the page is finished with, and before put_page is called.
  *
  * get_user_pages is typically used for fewer-copy IO operations, to get a
  * handle on the memory by some means other than accesses via the user virtual
@@ -965,18 +963,12 @@ EXPORT_SYMBOL(get_user_pages_unlocked);
  */
 long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
 		unsigned long start, unsigned long nr_pages,
-		int write, int force, struct page **pages,
+		unsigned int gup_flags, struct page **pages,
 		struct vm_area_struct **vmas)
 {
-	unsigned int flags = FOLL_TOUCH | FOLL_REMOTE;
-
-	if (write)
-		flags |= FOLL_WRITE;
-	if (force)
-		flags |= FOLL_FORCE;
-
 	return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
-				       NULL, false, flags);
+				       NULL, false,
+				       gup_flags | FOLL_TOUCH | FOLL_REMOTE);
 }
 EXPORT_SYMBOL(get_user_pages_remote);
 
diff --git a/mm/memory.c b/mm/memory.c
index fc1987dfd8cc..20a9adb7b36e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3873,6 +3873,10 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
 {
 	struct vm_area_struct *vma;
 	void *old_buf = buf;
+	unsigned int flags = FOLL_FORCE;
+
+	if (write)
+		flags |= FOLL_WRITE;
 
 	down_read(&mm->mmap_sem);
 	/* ignore errors, just check how much was successfully transferred */
@@ -3882,7 +3886,7 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
 		struct page *page = NULL;
 
 		ret = get_user_pages_remote(tsk, mm, addr, 1,
-				write, 1, &page, &vma);
+				flags, &page, &vma);
 		if (ret <= 0) {
 #ifndef CONFIG_HAVE_IOREMAP_PROT
 			break;
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index ade7c6cad172..682b73af7766 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -881,7 +881,7 @@ bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos,
 	 * the execve().
 	 */
 	if (get_user_pages_remote(current, bprm->mm, pos, 1,
-				0, 1, &page, NULL) <= 0)
+				FOLL_FORCE, &page, NULL) <= 0)
 		return false;
 #else
 	page = bprm->page[pos / PAGE_SIZE];
-- 
cgit v1.2.3-70-g09d2


From 6347e8d5bcce33fc36e651901efefbe2c93a43ef Mon Sep 17 00:00:00 2001
From: Lorenzo Stoakes <lstoakes@gmail.com>
Date: Thu, 13 Oct 2016 01:20:19 +0100
Subject: mm: replace access_remote_vm() write parameter with gup_flags

This removes the 'write' argument from access_remote_vm() and replaces
it with 'gup_flags' as use of this function previously silently implied
FOLL_FORCE, whereas after this patch callers explicitly pass this flag.

We make this explicit as use of FOLL_FORCE can result in surprising
behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 fs/proc/base.c     | 19 +++++++++++++------
 include/linux/mm.h |  2 +-
 mm/memory.c        | 11 +++--------
 mm/nommu.c         |  7 +++----
 4 files changed, 20 insertions(+), 19 deletions(-)

(limited to 'include')

diff --git a/fs/proc/base.c b/fs/proc/base.c
index c2964d890c9a..8e654468ab67 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -252,7 +252,7 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
 	 * Inherently racy -- command line shares address space
 	 * with code and data.
 	 */
-	rv = access_remote_vm(mm, arg_end - 1, &c, 1, 0);
+	rv = access_remote_vm(mm, arg_end - 1, &c, 1, FOLL_FORCE);
 	if (rv <= 0)
 		goto out_free_page;
 
@@ -270,7 +270,8 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
 			int nr_read;
 
 			_count = min3(count, len, PAGE_SIZE);
-			nr_read = access_remote_vm(mm, p, page, _count, 0);
+			nr_read = access_remote_vm(mm, p, page, _count,
+					FOLL_FORCE);
 			if (nr_read < 0)
 				rv = nr_read;
 			if (nr_read <= 0)
@@ -305,7 +306,8 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
 			bool final;
 
 			_count = min3(count, len, PAGE_SIZE);
-			nr_read = access_remote_vm(mm, p, page, _count, 0);
+			nr_read = access_remote_vm(mm, p, page, _count,
+					FOLL_FORCE);
 			if (nr_read < 0)
 				rv = nr_read;
 			if (nr_read <= 0)
@@ -354,7 +356,8 @@ skip_argv:
 			bool final;
 
 			_count = min3(count, len, PAGE_SIZE);
-			nr_read = access_remote_vm(mm, p, page, _count, 0);
+			nr_read = access_remote_vm(mm, p, page, _count,
+					FOLL_FORCE);
 			if (nr_read < 0)
 				rv = nr_read;
 			if (nr_read <= 0)
@@ -832,6 +835,7 @@ static ssize_t mem_rw(struct file *file, char __user *buf,
 	unsigned long addr = *ppos;
 	ssize_t copied;
 	char *page;
+	unsigned int flags = FOLL_FORCE;
 
 	if (!mm)
 		return 0;
@@ -844,6 +848,9 @@ static ssize_t mem_rw(struct file *file, char __user *buf,
 	if (!atomic_inc_not_zero(&mm->mm_users))
 		goto free;
 
+	if (write)
+		flags |= FOLL_WRITE;
+
 	while (count > 0) {
 		int this_len = min_t(int, count, PAGE_SIZE);
 
@@ -852,7 +859,7 @@ static ssize_t mem_rw(struct file *file, char __user *buf,
 			break;
 		}
 
-		this_len = access_remote_vm(mm, addr, page, this_len, write);
+		this_len = access_remote_vm(mm, addr, page, this_len, flags);
 		if (!this_len) {
 			if (!copied)
 				copied = -EIO;
@@ -965,7 +972,7 @@ static ssize_t environ_read(struct file *file, char __user *buf,
 		this_len = min(max_len, this_len);
 
 		retval = access_remote_vm(mm, (env_start + src),
-			page, this_len, 0);
+			page, this_len, FOLL_FORCE);
 
 		if (retval <= 0) {
 			ret = retval;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ecc4be7b67e0..f31bf9058587 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1268,7 +1268,7 @@ static inline int fixup_user_fault(struct task_struct *tsk,
 
 extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write);
 extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,
-		void *buf, int len, int write);
+		void *buf, int len, unsigned int gup_flags);
 
 long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 		      unsigned long start, unsigned long nr_pages,
diff --git a/mm/memory.c b/mm/memory.c
index 79ebed3a4c2b..bac2d994850e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3935,19 +3935,14 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
  * @addr:	start address to access
  * @buf:	source or destination buffer
  * @len:	number of bytes to transfer
- * @write:	whether the access is a write
+ * @gup_flags:	flags modifying lookup behaviour
  *
  * The caller must hold a reference on @mm.
  */
 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
-		void *buf, int len, int write)
+		void *buf, int len, unsigned int gup_flags)
 {
-	unsigned int flags = FOLL_FORCE;
-
-	if (write)
-		flags |= FOLL_WRITE;
-
-	return __access_remote_vm(NULL, mm, addr, buf, len, flags);
+	return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
 }
 
 /*
diff --git a/mm/nommu.c b/mm/nommu.c
index bde7df35118b..93d5bb53fc63 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1847,15 +1847,14 @@ static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
  * @addr:	start address to access
  * @buf:	source or destination buffer
  * @len:	number of bytes to transfer
- * @write:	whether the access is a write
+ * @gup_flags:	flags modifying lookup behaviour
  *
  * The caller must hold a reference on @mm.
  */
 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
-		void *buf, int len, int write)
+		void *buf, int len, unsigned int gup_flags)
 {
-	return __access_remote_vm(NULL, mm, addr, buf, len,
-			write ? FOLL_WRITE : 0);
+	return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
 }
 
 /*
-- 
cgit v1.2.3-70-g09d2


From f307ab6dcea03f9d8e4d70508fd7d1ca57cfa7f9 Mon Sep 17 00:00:00 2001
From: Lorenzo Stoakes <lstoakes@gmail.com>
Date: Thu, 13 Oct 2016 01:20:20 +0100
Subject: mm: replace access_process_vm() write parameter with gup_flags

This removes the 'write' argument from access_process_vm() and replaces
it with 'gup_flags' as use of this function previously silently implied
FOLL_FORCE, whereas after this patch callers explicitly pass this flag.

We make this explicit as use of FOLL_FORCE can result in surprising
behaviour (and hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 arch/alpha/kernel/ptrace.c         |  9 ++++++---
 arch/blackfin/kernel/ptrace.c      |  5 +++--
 arch/cris/arch-v32/kernel/ptrace.c |  4 ++--
 arch/ia64/kernel/ptrace.c          | 14 +++++++++-----
 arch/m32r/kernel/ptrace.c          | 15 ++++++++++-----
 arch/mips/kernel/ptrace32.c        |  5 +++--
 arch/powerpc/kernel/ptrace32.c     |  5 +++--
 arch/score/kernel/ptrace.c         | 10 ++++++----
 arch/sparc/kernel/ptrace_64.c      | 24 ++++++++++++++++--------
 arch/x86/kernel/step.c             |  3 ++-
 arch/x86/um/ptrace_32.c            |  3 ++-
 arch/x86/um/ptrace_64.c            |  3 ++-
 include/linux/mm.h                 |  3 ++-
 kernel/ptrace.c                    | 16 ++++++++++------
 mm/memory.c                        |  8 ++------
 mm/nommu.c                         |  6 +++---
 mm/util.c                          |  5 +++--
 17 files changed, 84 insertions(+), 54 deletions(-)

(limited to 'include')

diff --git a/arch/alpha/kernel/ptrace.c b/arch/alpha/kernel/ptrace.c
index d9ee81769899..940dfb406591 100644
--- a/arch/alpha/kernel/ptrace.c
+++ b/arch/alpha/kernel/ptrace.c
@@ -157,14 +157,16 @@ put_reg(struct task_struct *task, unsigned long regno, unsigned long data)
 static inline int
 read_int(struct task_struct *task, unsigned long addr, int * data)
 {
-	int copied = access_process_vm(task, addr, data, sizeof(int), 0);
+	int copied = access_process_vm(task, addr, data, sizeof(int),
+			FOLL_FORCE);
 	return (copied == sizeof(int)) ? 0 : -EIO;
 }
 
 static inline int
 write_int(struct task_struct *task, unsigned long addr, int data)
 {
-	int copied = access_process_vm(task, addr, &data, sizeof(int), 1);
+	int copied = access_process_vm(task, addr, &data, sizeof(int),
+			FOLL_FORCE | FOLL_WRITE);
 	return (copied == sizeof(int)) ? 0 : -EIO;
 }
 
@@ -281,7 +283,8 @@ long arch_ptrace(struct task_struct *child, long request,
 	/* When I and D space are separate, these will need to be fixed.  */
 	case PTRACE_PEEKTEXT: /* read word at location addr. */
 	case PTRACE_PEEKDATA:
-		copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
+		copied = access_process_vm(child, addr, &tmp, sizeof(tmp),
+				FOLL_FORCE);
 		ret = -EIO;
 		if (copied != sizeof(tmp))
 			break;
diff --git a/arch/blackfin/kernel/ptrace.c b/arch/blackfin/kernel/ptrace.c
index 8b8fe671b1a6..8d79286ee4e8 100644
--- a/arch/blackfin/kernel/ptrace.c
+++ b/arch/blackfin/kernel/ptrace.c
@@ -271,7 +271,7 @@ long arch_ptrace(struct task_struct *child, long request,
 			case BFIN_MEM_ACCESS_CORE:
 			case BFIN_MEM_ACCESS_CORE_ONLY:
 				copied = access_process_vm(child, addr, &tmp,
-				                           to_copy, 0);
+							   to_copy, FOLL_FORCE);
 				if (copied)
 					break;
 
@@ -324,7 +324,8 @@ long arch_ptrace(struct task_struct *child, long request,
 			case BFIN_MEM_ACCESS_CORE:
 			case BFIN_MEM_ACCESS_CORE_ONLY:
 				copied = access_process_vm(child, addr, &data,
-				                           to_copy, 1);
+				                           to_copy,
+							   FOLL_FORCE | FOLL_WRITE);
 				break;
 			case BFIN_MEM_ACCESS_DMA:
 				if (safe_dma_memcpy(paddr, &data, to_copy))
diff --git a/arch/cris/arch-v32/kernel/ptrace.c b/arch/cris/arch-v32/kernel/ptrace.c
index f085229cf870..f0df654ac6fc 100644
--- a/arch/cris/arch-v32/kernel/ptrace.c
+++ b/arch/cris/arch-v32/kernel/ptrace.c
@@ -147,7 +147,7 @@ long arch_ptrace(struct task_struct *child, long request,
 				/* The trampoline page is globally mapped, no page table to traverse.*/
 				tmp = *(unsigned long*)addr;
 			} else {
-				copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
+				copied = access_process_vm(child, addr, &tmp, sizeof(tmp), FOLL_FORCE);
 
 				if (copied != sizeof(tmp))
 					break;
@@ -279,7 +279,7 @@ static int insn_size(struct task_struct *child, unsigned long pc)
   int opsize = 0;
 
   /* Read the opcode at pc (do what PTRACE_PEEKTEXT would do). */
-  copied = access_process_vm(child, pc, &opcode, sizeof(opcode), 0);
+  copied = access_process_vm(child, pc, &opcode, sizeof(opcode), FOLL_FORCE);
   if (copied != sizeof(opcode))
     return 0;
 
diff --git a/arch/ia64/kernel/ptrace.c b/arch/ia64/kernel/ptrace.c
index 6f54d511cc50..31aa8c0f68e1 100644
--- a/arch/ia64/kernel/ptrace.c
+++ b/arch/ia64/kernel/ptrace.c
@@ -453,7 +453,7 @@ ia64_peek (struct task_struct *child, struct switch_stack *child_stack,
 			return 0;
 		}
 	}
-	copied = access_process_vm(child, addr, &ret, sizeof(ret), 0);
+	copied = access_process_vm(child, addr, &ret, sizeof(ret), FOLL_FORCE);
 	if (copied != sizeof(ret))
 		return -EIO;
 	*val = ret;
@@ -489,7 +489,8 @@ ia64_poke (struct task_struct *child, struct switch_stack *child_stack,
 				*ia64_rse_skip_regs(krbs, regnum) = val;
 			}
 		}
-	} else if (access_process_vm(child, addr, &val, sizeof(val), 1)
+	} else if (access_process_vm(child, addr, &val, sizeof(val),
+				FOLL_FORCE | FOLL_WRITE)
 		   != sizeof(val))
 		return -EIO;
 	return 0;
@@ -543,7 +544,8 @@ ia64_sync_user_rbs (struct task_struct *child, struct switch_stack *sw,
 		ret = ia64_peek(child, sw, user_rbs_end, addr, &val);
 		if (ret < 0)
 			return ret;
-		if (access_process_vm(child, addr, &val, sizeof(val), 1)
+		if (access_process_vm(child, addr, &val, sizeof(val),
+				FOLL_FORCE | FOLL_WRITE)
 		    != sizeof(val))
 			return -EIO;
 	}
@@ -559,7 +561,8 @@ ia64_sync_kernel_rbs (struct task_struct *child, struct switch_stack *sw,
 
 	/* now copy word for word from user rbs to kernel rbs: */
 	for (addr = user_rbs_start; addr < user_rbs_end; addr += 8) {
-		if (access_process_vm(child, addr, &val, sizeof(val), 0)
+		if (access_process_vm(child, addr, &val, sizeof(val),
+				FOLL_FORCE)
 				!= sizeof(val))
 			return -EIO;
 
@@ -1156,7 +1159,8 @@ arch_ptrace (struct task_struct *child, long request,
 	case PTRACE_PEEKTEXT:
 	case PTRACE_PEEKDATA:
 		/* read word at location addr */
-		if (access_process_vm(child, addr, &data, sizeof(data), 0)
+		if (access_process_vm(child, addr, &data, sizeof(data),
+				FOLL_FORCE)
 		    != sizeof(data))
 			return -EIO;
 		/* ensure return value is not mistaken for error code */
diff --git a/arch/m32r/kernel/ptrace.c b/arch/m32r/kernel/ptrace.c
index 51f5e9aa4901..c145605a981f 100644
--- a/arch/m32r/kernel/ptrace.c
+++ b/arch/m32r/kernel/ptrace.c
@@ -493,7 +493,8 @@ unregister_all_debug_traps(struct task_struct *child)
 	int i;
 
 	for (i = 0; i < p->nr_trap; i++)
-		access_process_vm(child, p->addr[i], &p->insn[i], sizeof(p->insn[i]), 1);
+		access_process_vm(child, p->addr[i], &p->insn[i], sizeof(p->insn[i]),
+				FOLL_FORCE | FOLL_WRITE);
 	p->nr_trap = 0;
 }
 
@@ -537,7 +538,8 @@ embed_debug_trap(struct task_struct *child, unsigned long next_pc)
 	unsigned long next_insn, code;
 	unsigned long addr = next_pc & ~3;
 
-	if (access_process_vm(child, addr, &next_insn, sizeof(next_insn), 0)
+	if (access_process_vm(child, addr, &next_insn, sizeof(next_insn),
+			FOLL_FORCE)
 	    != sizeof(next_insn)) {
 		return -1; /* error */
 	}
@@ -546,7 +548,8 @@ embed_debug_trap(struct task_struct *child, unsigned long next_pc)
 	if (register_debug_trap(child, next_pc, next_insn, &code)) {
 		return -1; /* error */
 	}
-	if (access_process_vm(child, addr, &code, sizeof(code), 1)
+	if (access_process_vm(child, addr, &code, sizeof(code),
+			FOLL_FORCE | FOLL_WRITE)
 	    != sizeof(code)) {
 		return -1; /* error */
 	}
@@ -562,7 +565,8 @@ withdraw_debug_trap(struct pt_regs *regs)
  	addr = (regs->bpc - 2) & ~3;
 	regs->bpc -= 2;
 	if (unregister_debug_trap(current, addr, &code)) {
-	    access_process_vm(current, addr, &code, sizeof(code), 1);
+	    access_process_vm(current, addr, &code, sizeof(code),
+		    FOLL_FORCE | FOLL_WRITE);
 	    invalidate_cache();
 	}
 }
@@ -589,7 +593,8 @@ void user_enable_single_step(struct task_struct *child)
 	/* Compute next pc.  */
 	pc = get_stack_long(child, PT_BPC);
 
-	if (access_process_vm(child, pc&~3, &insn, sizeof(insn), 0)
+	if (access_process_vm(child, pc&~3, &insn, sizeof(insn),
+			FOLL_FORCE)
 	    != sizeof(insn))
 		return;
 
diff --git a/arch/mips/kernel/ptrace32.c b/arch/mips/kernel/ptrace32.c
index 283b5a1967d1..7e71a4e0281b 100644
--- a/arch/mips/kernel/ptrace32.c
+++ b/arch/mips/kernel/ptrace32.c
@@ -70,7 +70,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 			break;
 
 		copied = access_process_vm(child, (u64)addrOthers, &tmp,
-				sizeof(tmp), 0);
+				sizeof(tmp), FOLL_FORCE);
 		if (copied != sizeof(tmp))
 			break;
 		ret = put_user(tmp, (u32 __user *) (unsigned long) data);
@@ -179,7 +179,8 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 			break;
 		ret = 0;
 		if (access_process_vm(child, (u64)addrOthers, &data,
-					sizeof(data), 1) == sizeof(data))
+					sizeof(data),
+					FOLL_FORCE | FOLL_WRITE) == sizeof(data))
 			break;
 		ret = -EIO;
 		break;
diff --git a/arch/powerpc/kernel/ptrace32.c b/arch/powerpc/kernel/ptrace32.c
index f52b7db327c8..010b7b310237 100644
--- a/arch/powerpc/kernel/ptrace32.c
+++ b/arch/powerpc/kernel/ptrace32.c
@@ -74,7 +74,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 			break;
 
 		copied = access_process_vm(child, (u64)addrOthers, &tmp,
-				sizeof(tmp), 0);
+				sizeof(tmp), FOLL_FORCE);
 		if (copied != sizeof(tmp))
 			break;
 		ret = put_user(tmp, (u32 __user *)data);
@@ -179,7 +179,8 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 			break;
 		ret = 0;
 		if (access_process_vm(child, (u64)addrOthers, &tmp,
-					sizeof(tmp), 1) == sizeof(tmp))
+					sizeof(tmp),
+					FOLL_FORCE | FOLL_WRITE) == sizeof(tmp))
 			break;
 		ret = -EIO;
 		break;
diff --git a/arch/score/kernel/ptrace.c b/arch/score/kernel/ptrace.c
index 55836188b217..4f7314d5f334 100644
--- a/arch/score/kernel/ptrace.c
+++ b/arch/score/kernel/ptrace.c
@@ -131,7 +131,7 @@ read_tsk_long(struct task_struct *child,
 {
 	int copied;
 
-	copied = access_process_vm(child, addr, res, sizeof(*res), 0);
+	copied = access_process_vm(child, addr, res, sizeof(*res), FOLL_FORCE);
 
 	return copied != sizeof(*res) ? -EIO : 0;
 }
@@ -142,7 +142,7 @@ read_tsk_short(struct task_struct *child,
 {
 	int copied;
 
-	copied = access_process_vm(child, addr, res, sizeof(*res), 0);
+	copied = access_process_vm(child, addr, res, sizeof(*res), FOLL_FORCE);
 
 	return copied != sizeof(*res) ? -EIO : 0;
 }
@@ -153,7 +153,8 @@ write_tsk_short(struct task_struct *child,
 {
 	int copied;
 
-	copied = access_process_vm(child, addr, &val, sizeof(val), 1);
+	copied = access_process_vm(child, addr, &val, sizeof(val),
+			FOLL_FORCE | FOLL_WRITE);
 
 	return copied != sizeof(val) ? -EIO : 0;
 }
@@ -164,7 +165,8 @@ write_tsk_long(struct task_struct *child,
 {
 	int copied;
 
-	copied = access_process_vm(child, addr, &val, sizeof(val), 1);
+	copied = access_process_vm(child, addr, &val, sizeof(val),
+			FOLL_FORCE | FOLL_WRITE);
 
 	return copied != sizeof(val) ? -EIO : 0;
 }
diff --git a/arch/sparc/kernel/ptrace_64.c b/arch/sparc/kernel/ptrace_64.c
index 9ddc4928a089..ac082dd8c67d 100644
--- a/arch/sparc/kernel/ptrace_64.c
+++ b/arch/sparc/kernel/ptrace_64.c
@@ -127,7 +127,8 @@ static int get_from_target(struct task_struct *target, unsigned long uaddr,
 		if (copy_from_user(kbuf, (void __user *) uaddr, len))
 			return -EFAULT;
 	} else {
-		int len2 = access_process_vm(target, uaddr, kbuf, len, 0);
+		int len2 = access_process_vm(target, uaddr, kbuf, len,
+				FOLL_FORCE);
 		if (len2 != len)
 			return -EFAULT;
 	}
@@ -141,7 +142,8 @@ static int set_to_target(struct task_struct *target, unsigned long uaddr,
 		if (copy_to_user((void __user *) uaddr, kbuf, len))
 			return -EFAULT;
 	} else {
-		int len2 = access_process_vm(target, uaddr, kbuf, len, 1);
+		int len2 = access_process_vm(target, uaddr, kbuf, len,
+				FOLL_FORCE | FOLL_WRITE);
 		if (len2 != len)
 			return -EFAULT;
 	}
@@ -505,7 +507,8 @@ static int genregs32_get(struct task_struct *target,
 				if (access_process_vm(target,
 						      (unsigned long)
 						      &reg_window[pos],
-						      k, sizeof(*k), 0)
+						      k, sizeof(*k),
+						      FOLL_FORCE)
 				    != sizeof(*k))
 					return -EFAULT;
 				k++;
@@ -531,12 +534,14 @@ static int genregs32_get(struct task_struct *target,
 				if (access_process_vm(target,
 						      (unsigned long)
 						      &reg_window[pos],
-						      &reg, sizeof(reg), 0)
+						      &reg, sizeof(reg),
+						      FOLL_FORCE)
 				    != sizeof(reg))
 					return -EFAULT;
 				if (access_process_vm(target,
 						      (unsigned long) u,
-						      &reg, sizeof(reg), 1)
+						      &reg, sizeof(reg),
+						      FOLL_FORCE | FOLL_WRITE)
 				    != sizeof(reg))
 					return -EFAULT;
 				pos++;
@@ -615,7 +620,8 @@ static int genregs32_set(struct task_struct *target,
 						      (unsigned long)
 						      &reg_window[pos],
 						      (void *) k,
-						      sizeof(*k), 1)
+						      sizeof(*k),
+						      FOLL_FORCE | FOLL_WRITE)
 				    != sizeof(*k))
 					return -EFAULT;
 				k++;
@@ -642,13 +648,15 @@ static int genregs32_set(struct task_struct *target,
 				if (access_process_vm(target,
 						      (unsigned long)
 						      u,
-						      &reg, sizeof(reg), 0)
+						      &reg, sizeof(reg),
+						      FOLL_FORCE)
 				    != sizeof(reg))
 					return -EFAULT;
 				if (access_process_vm(target,
 						      (unsigned long)
 						      &reg_window[pos],
-						      &reg, sizeof(reg), 1)
+						      &reg, sizeof(reg),
+						      FOLL_FORCE | FOLL_WRITE)
 				    != sizeof(reg))
 					return -EFAULT;
 				pos++;
diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c
index c9a073866ca7..a23ce84a3f6c 100644
--- a/arch/x86/kernel/step.c
+++ b/arch/x86/kernel/step.c
@@ -57,7 +57,8 @@ static int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs)
 	unsigned char opcode[15];
 	unsigned long addr = convert_ip_to_linear(child, regs);
 
-	copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0);
+	copied = access_process_vm(child, addr, opcode, sizeof(opcode),
+			FOLL_FORCE);
 	for (i = 0; i < copied; i++) {
 		switch (opcode[i]) {
 		/* popf and iret */
diff --git a/arch/x86/um/ptrace_32.c b/arch/x86/um/ptrace_32.c
index 5766ead6fdb9..60a5a5a85505 100644
--- a/arch/x86/um/ptrace_32.c
+++ b/arch/x86/um/ptrace_32.c
@@ -36,7 +36,8 @@ int is_syscall(unsigned long addr)
 		 * slow, but that doesn't matter, since it will be called only
 		 * in case of singlestepping, if copy_from_user failed.
 		 */
-		n = access_process_vm(current, addr, &instr, sizeof(instr), 0);
+		n = access_process_vm(current, addr, &instr, sizeof(instr),
+				FOLL_FORCE);
 		if (n != sizeof(instr)) {
 			printk(KERN_ERR "is_syscall : failed to read "
 			       "instruction from 0x%lx\n", addr);
diff --git a/arch/x86/um/ptrace_64.c b/arch/x86/um/ptrace_64.c
index 0b5c184dd5b3..e30202b1716e 100644
--- a/arch/x86/um/ptrace_64.c
+++ b/arch/x86/um/ptrace_64.c
@@ -212,7 +212,8 @@ int is_syscall(unsigned long addr)
 		 * slow, but that doesn't matter, since it will be called only
 		 * in case of singlestepping, if copy_from_user failed.
 		 */
-		n = access_process_vm(current, addr, &instr, sizeof(instr), 0);
+		n = access_process_vm(current, addr, &instr, sizeof(instr),
+				FOLL_FORCE);
 		if (n != sizeof(instr)) {
 			printk("is_syscall : failed to read instruction from "
 			       "0x%lx\n", addr);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index f31bf9058587..ffbd72979ee7 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1266,7 +1266,8 @@ static inline int fixup_user_fault(struct task_struct *tsk,
 }
 #endif
 
-extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write);
+extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len,
+		unsigned int gup_flags);
 extern int access_remote_vm(struct mm_struct *mm, unsigned long addr,
 		void *buf, int len, unsigned int gup_flags);
 
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 2a99027312a6..e6474f7272ec 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -537,7 +537,7 @@ int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst
 		int this_len, retval;
 
 		this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
-		retval = access_process_vm(tsk, src, buf, this_len, 0);
+		retval = access_process_vm(tsk, src, buf, this_len, FOLL_FORCE);
 		if (!retval) {
 			if (copied)
 				break;
@@ -564,7 +564,8 @@ int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long ds
 		this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
 		if (copy_from_user(buf, src, this_len))
 			return -EFAULT;
-		retval = access_process_vm(tsk, dst, buf, this_len, 1);
+		retval = access_process_vm(tsk, dst, buf, this_len,
+				FOLL_FORCE | FOLL_WRITE);
 		if (!retval) {
 			if (copied)
 				break;
@@ -1127,7 +1128,7 @@ int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
 	unsigned long tmp;
 	int copied;
 
-	copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), 0);
+	copied = access_process_vm(tsk, addr, &tmp, sizeof(tmp), FOLL_FORCE);
 	if (copied != sizeof(tmp))
 		return -EIO;
 	return put_user(tmp, (unsigned long __user *)data);
@@ -1138,7 +1139,8 @@ int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
 {
 	int copied;
 
-	copied = access_process_vm(tsk, addr, &data, sizeof(data), 1);
+	copied = access_process_vm(tsk, addr, &data, sizeof(data),
+			FOLL_FORCE | FOLL_WRITE);
 	return (copied == sizeof(data)) ? 0 : -EIO;
 }
 
@@ -1155,7 +1157,8 @@ int compat_ptrace_request(struct task_struct *child, compat_long_t request,
 	switch (request) {
 	case PTRACE_PEEKTEXT:
 	case PTRACE_PEEKDATA:
-		ret = access_process_vm(child, addr, &word, sizeof(word), 0);
+		ret = access_process_vm(child, addr, &word, sizeof(word),
+				FOLL_FORCE);
 		if (ret != sizeof(word))
 			ret = -EIO;
 		else
@@ -1164,7 +1167,8 @@ int compat_ptrace_request(struct task_struct *child, compat_long_t request,
 
 	case PTRACE_POKETEXT:
 	case PTRACE_POKEDATA:
-		ret = access_process_vm(child, addr, &data, sizeof(data), 1);
+		ret = access_process_vm(child, addr, &data, sizeof(data),
+				FOLL_FORCE | FOLL_WRITE);
 		ret = (ret != sizeof(data) ? -EIO : 0);
 		break;
 
diff --git a/mm/memory.c b/mm/memory.c
index bac2d994850e..e18c57bdc75c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3951,20 +3951,16 @@ int access_remote_vm(struct mm_struct *mm, unsigned long addr,
  * Do not walk the page table directly, use get_user_pages
  */
 int access_process_vm(struct task_struct *tsk, unsigned long addr,
-		void *buf, int len, int write)
+		void *buf, int len, unsigned int gup_flags)
 {
 	struct mm_struct *mm;
 	int ret;
-	unsigned int flags = FOLL_FORCE;
 
 	mm = get_task_mm(tsk);
 	if (!mm)
 		return 0;
 
-	if (write)
-		flags |= FOLL_WRITE;
-
-	ret = __access_remote_vm(tsk, mm, addr, buf, len, flags);
+	ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
 
 	mmput(mm);
 
diff --git a/mm/nommu.c b/mm/nommu.c
index 93d5bb53fc63..db5fd1795298 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1861,7 +1861,8 @@ int access_remote_vm(struct mm_struct *mm, unsigned long addr,
  * Access another process' address space.
  * - source/target buffer must be kernel space
  */
-int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
+int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len,
+		unsigned int gup_flags)
 {
 	struct mm_struct *mm;
 
@@ -1872,8 +1873,7 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
 	if (!mm)
 		return 0;
 
-	len = __access_remote_vm(tsk, mm, addr, buf, len,
-			write ? FOLL_WRITE : 0);
+	len = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
 
 	mmput(mm);
 	return len;
diff --git a/mm/util.c b/mm/util.c
index 4c685bde5ebc..952cbe7ad7b7 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -624,7 +624,7 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen)
 	if (len > buflen)
 		len = buflen;
 
-	res = access_process_vm(task, arg_start, buffer, len, 0);
+	res = access_process_vm(task, arg_start, buffer, len, FOLL_FORCE);
 
 	/*
 	 * If the nul at the end of args has been overwritten, then
@@ -639,7 +639,8 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen)
 			if (len > buflen - res)
 				len = buflen - res;
 			res += access_process_vm(task, env_start,
-						 buffer+res, len, 0);
+						 buffer+res, len,
+						 FOLL_FORCE);
 			res = strnlen(buffer, res);
 		}
 	}
-- 
cgit v1.2.3-70-g09d2