In preparation for exporting per-arch mmap randomization functions,
this moves the ASLR calculations for mmap on ARM into a separate routine.
Signed-off-by: Kees Cook <keesc...@chromium.org>
---
arch/arm/mm/mmap.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index 5e85ed371364..0f8bc158f2c6 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -169,14 +169,21 @@ arch_get_unmapped_area_topdown(struct file *filp, const
unsigned long addr0,
return addr;
}
-void arch_pick_mmap_layout(struct mm_struct *mm)
+static unsigned long mmap_rnd(void)
{
- unsigned long random_factor = 0UL;
+ unsigned long rnd = 0UL;
/* 8 bits of randomness in 20 address space bits */
if ((current->flags & PF_RANDOMIZE) &&
!(current->personality & ADDR_NO_RANDOMIZE))
- random_factor = (get_random_int() % (1 << 8)) << PAGE_SHIFT;
+ rnd = (get_random_int() % (1 << 8)) << PAGE_SHIFT;
+
+ return rnd;
+}
+
+void arch_pick_mmap_layout(struct mm_struct *mm)
+{
+ unsigned long random_factor = mmap_rnd();
if (mmap_is_legacy()) {
mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
--
1.9.1
--
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