From 46aea3873401836abb7f01200e7946e7d518b359 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Thu, 14 Jul 2016 13:22:54 -0700 Subject: x86/mm/64: In vmalloc_fault(), use CR3 instead of current->active_mm If we get a vmalloc fault while current->active_mm->pgd doesn't match CR3, we'll crash without this change. I've seen this failure mode on heavily instrumented kernels with virtually mapped stacks. Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/4650d7674185f165ed8fdf9ac4c5c35c5c179ba8.1468527351.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/mm/fault.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/mm/fault.c') diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 7d1fa7cd2374..ca44e2e7fd00 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -439,7 +439,7 @@ static noinline int vmalloc_fault(unsigned long address) * happen within a race in page table update. In the later * case just flush: */ - pgd = pgd_offset(current->active_mm, address); + pgd = (pgd_t *)__va(read_cr3()) + pgd_index(address); pgd_ref = pgd_offset_k(address); if (pgd_none(*pgd_ref)) return -1; -- cgit v1.2.3-70-g09d2 From dfa9a942fd7951c8f333cf3f377dde51ebd21685 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Thu, 14 Jul 2016 13:22:56 -0700 Subject: x86/uaccess: Move thread_info::uaccess_err and thread_info::sig_on_uaccess_err to thread_struct struct thread_info is a legacy mess. To prepare for its partial removal, move the uaccess control fields out -- they're straightforward. Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/d0ac4d01c8e4d4d756264604e47445d5acc7900e.1468527351.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/entry/vsyscall/vsyscall_64.c | 6 +++--- arch/x86/include/asm/processor.h | 3 +++ arch/x86/include/asm/thread_info.h | 2 -- arch/x86/include/asm/uaccess.h | 4 ++-- arch/x86/mm/extable.c | 2 +- arch/x86/mm/fault.c | 2 +- 6 files changed, 10 insertions(+), 9 deletions(-) (limited to 'arch/x86/mm/fault.c') diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c index 174c2549939d..3aba2b043050 100644 --- a/arch/x86/entry/vsyscall/vsyscall_64.c +++ b/arch/x86/entry/vsyscall/vsyscall_64.c @@ -221,8 +221,8 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address) * With a real vsyscall, page faults cause SIGSEGV. We want to * preserve that behavior to make writing exploits harder. */ - prev_sig_on_uaccess_error = current_thread_info()->sig_on_uaccess_error; - current_thread_info()->sig_on_uaccess_error = 1; + prev_sig_on_uaccess_error = current->thread.sig_on_uaccess_error; + current->thread.sig_on_uaccess_error = 1; ret = -EFAULT; switch (vsyscall_nr) { @@ -243,7 +243,7 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address) break; } - current_thread_info()->sig_on_uaccess_error = prev_sig_on_uaccess_error; + current->thread.sig_on_uaccess_error = prev_sig_on_uaccess_error; check_fault: if (ret == -EFAULT) { diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 62c6cc3cc5d3..f53ae57bd985 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -419,6 +419,9 @@ struct thread_struct { /* Max allowed port in the bitmap, in bytes: */ unsigned io_bitmap_max; + unsigned int sig_on_uaccess_error:1; + unsigned int uaccess_err:1; /* uaccess failed */ + /* Floating point and extended processor state */ struct fpu fpu; /* diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index 30c133ac05cd..7c47bb659ecd 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -58,8 +58,6 @@ struct thread_info { __u32 status; /* thread synchronous flags */ __u32 cpu; /* current CPU */ mm_segment_t addr_limit; - unsigned int sig_on_uaccess_error:1; - unsigned int uaccess_err:1; /* uaccess failed */ }; #define INIT_THREAD_INFO(tsk) \ diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index d40ec723f799..8f66e5655c23 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -487,13 +487,13 @@ struct __large_struct { unsigned long buf[100]; }; * uaccess_try and catch */ #define uaccess_try do { \ - current_thread_info()->uaccess_err = 0; \ + current->thread.uaccess_err = 0; \ __uaccess_begin(); \ barrier(); #define uaccess_catch(err) \ __uaccess_end(); \ - (err) |= (current_thread_info()->uaccess_err ? -EFAULT : 0); \ + (err) |= (current->thread.uaccess_err ? -EFAULT : 0); \ } while (0) /** diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index 4bb53b89f3c5..0f90cc218d04 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -37,7 +37,7 @@ bool ex_handler_ext(const struct exception_table_entry *fixup, struct pt_regs *regs, int trapnr) { /* Special hack for uaccess_err */ - current_thread_info()->uaccess_err = 1; + current->thread.uaccess_err = 1; regs->ip = ex_fixup_addr(fixup); return true; } diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index ca44e2e7fd00..69be03d4aca6 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -737,7 +737,7 @@ no_context(struct pt_regs *regs, unsigned long error_code, * In this case we need to make sure we're not recursively * faulting through the emulate_vsyscall() logic. */ - if (current_thread_info()->sig_on_uaccess_error && signal) { + if (current->thread.sig_on_uaccess_error && signal) { tsk->thread.trap_nr = X86_TRAP_PF; tsk->thread.error_code = error_code | PF_USER; tsk->thread.cr2 = address; -- cgit v1.2.3-70-g09d2 From 2a53ccbc0de1b1950aeedd24680f7eca65c86ff5 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Fri, 15 Jul 2016 10:21:11 +0200 Subject: x86/dumpstack: Rename thread_struct::sig_on_uaccess_error to sig_on_uaccess_err Rename it to match the thread_struct::uaccess_err pattern and also because it was too long. Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar --- arch/x86/entry/vsyscall/vsyscall_64.c | 10 +++++----- arch/x86/include/asm/processor.h | 2 +- arch/x86/mm/fault.c | 2 +- 3 files changed, 7 insertions(+), 7 deletions(-) (limited to 'arch/x86/mm/fault.c') diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c index 3aba2b043050..75fc719b7f31 100644 --- a/arch/x86/entry/vsyscall/vsyscall_64.c +++ b/arch/x86/entry/vsyscall/vsyscall_64.c @@ -96,7 +96,7 @@ static bool write_ok_or_segv(unsigned long ptr, size_t size) { /* * XXX: if access_ok, get_user, and put_user handled - * sig_on_uaccess_error, this could go away. + * sig_on_uaccess_err, this could go away. */ if (!access_ok(VERIFY_WRITE, (void __user *)ptr, size)) { @@ -125,7 +125,7 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address) struct task_struct *tsk; unsigned long caller; int vsyscall_nr, syscall_nr, tmp; - int prev_sig_on_uaccess_error; + int prev_sig_on_uaccess_err; long ret; /* @@ -221,8 +221,8 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address) * With a real vsyscall, page faults cause SIGSEGV. We want to * preserve that behavior to make writing exploits harder. */ - prev_sig_on_uaccess_error = current->thread.sig_on_uaccess_error; - current->thread.sig_on_uaccess_error = 1; + prev_sig_on_uaccess_err = current->thread.sig_on_uaccess_err; + current->thread.sig_on_uaccess_err = 1; ret = -EFAULT; switch (vsyscall_nr) { @@ -243,7 +243,7 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address) break; } - current->thread.sig_on_uaccess_error = prev_sig_on_uaccess_error; + current->thread.sig_on_uaccess_err = prev_sig_on_uaccess_err; check_fault: if (ret == -EFAULT) { diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index f53ae57bd985..cbdfe5f76347 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -419,7 +419,7 @@ struct thread_struct { /* Max allowed port in the bitmap, in bytes: */ unsigned io_bitmap_max; - unsigned int sig_on_uaccess_error:1; + unsigned int sig_on_uaccess_err:1; unsigned int uaccess_err:1; /* uaccess failed */ /* Floating point and extended processor state */ diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 69be03d4aca6..d22161ab941d 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -737,7 +737,7 @@ no_context(struct pt_regs *regs, unsigned long error_code, * In this case we need to make sure we're not recursively * faulting through the emulate_vsyscall() logic. */ - if (current->thread.sig_on_uaccess_error && signal) { + if (current->thread.sig_on_uaccess_err && signal) { tsk->thread.trap_nr = X86_TRAP_PF; tsk->thread.error_code = error_code | PF_USER; tsk->thread.cr2 = address; -- cgit v1.2.3-70-g09d2