1 files changed, 50 insertions, 5 deletions

diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c
index 99694260cac9..5075cde77b29 100644
--- a/arch/s390/kernel/vdso.c
+++ b/arch/s390/kernel/vdso.c
@@ -16,6 +16,7 @@
 #include <linux/slab.h>
 #include <linux/smp.h>
 #include <linux/time_namespace.h>
+#include <linux/random.h>
 #include <vdso/datapage.h>
 #include <asm/vdso.h>
 
@@ -160,10 +161,9 @@ int vdso_getcpu_init(void)
 }
 early_initcall(vdso_getcpu_init); /* Must be called before SMP init */
 
-int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+static int map_vdso(unsigned long addr, unsigned long vdso_mapping_len)
 {
-	unsigned long vdso_text_len, vdso_mapping_len;
-	unsigned long vvar_start, vdso_text_start;
+	unsigned long vvar_start, vdso_text_start, vdso_text_len;
 	struct vm_special_mapping *vdso_mapping;
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
@@ -180,8 +180,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 		vdso_text_len = vdso64_end - vdso64_start;
 		vdso_mapping = &vdso64_mapping;
 	}
-	vdso_mapping_len = vdso_text_len + VVAR_NR_PAGES * PAGE_SIZE;
-	vvar_start = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
+	vvar_start = get_unmapped_area(NULL, addr, vdso_mapping_len, 0, 0);
 	rc = vvar_start;
 	if (IS_ERR_VALUE(vvar_start))
 		goto out;
@@ -210,6 +209,52 @@ out:
 	return rc;
 }
 
+static unsigned long vdso_addr(unsigned long start, unsigned long len)
+{
+	unsigned long addr, end, offset;
+
+	/*
+	 * Round up the start address. It can start out unaligned as a result
+	 * of stack start randomization.
+	 */
+	start = PAGE_ALIGN(start);
+
+	/* Round the lowest possible end address up to a PMD boundary. */
+	end = (start + len + PMD_SIZE - 1) & PMD_MASK;
+	if (end >= VDSO_BASE)
+		end = VDSO_BASE;
+	end -= len;
+
+	if (end > start) {
+		offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1);
+		addr = start + (offset << PAGE_SHIFT);
+	} else {
+		addr = start;
+	}
+	return addr;
+}
+
+unsigned long vdso_size(void)
+{
+	unsigned long size = VVAR_NR_PAGES * PAGE_SIZE;
+
+	if (is_compat_task())
+		size += vdso32_end - vdso32_start;
+	else
+		size += vdso64_end - vdso64_start;
+	return PAGE_ALIGN(size);
+}
+
+int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+{
+	unsigned long addr = VDSO_BASE;
+	unsigned long size = vdso_size();
+
+	if (current->flags & PF_RANDOMIZE)
+		addr = vdso_addr(current->mm->start_stack + PAGE_SIZE, size);
+	return map_vdso(addr, size);
+}
+
 static struct page ** __init vdso_setup_pages(void *start, void *end)
 {
 	int pages = (end - start) >> PAGE_SHIFT;