3.19.8-ckt21 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Kees Cook <keescook@xxxxxxxxxxxx>
commit 1f0569df0b0285e7ec2432d804a4921b06a61618 upstream.
In preparation for splitting out ET_DYN ASLR, extract the mmap ASLR
selection into a separate function.
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
arch/mips/mm/mmap.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)
diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
index f1baadd..9a4f1f5 100644
--- a/arch/mips/mm/mmap.c
+++ b/arch/mips/mm/mmap.c
@@ -142,18 +142,26 @@ unsigned long arch_get_unmapped_area_topdown(struct file *filp,
addr0, len, pgoff, flags, DOWN);
}
+static unsigned long mmap_rnd(void)
+{
+ unsigned long rnd;
+
+ rnd = (unsigned long)get_random_int();
+ rnd <<= PAGE_SHIFT;
+ if (TASK_IS_32BIT_ADDR)
+ rnd &= 0xfffffful;
+ else
+ rnd &= 0xffffffful;
+
+ return rnd;
+}
+
void arch_pick_mmap_layout(struct mm_struct *mm)
{
unsigned long random_factor = 0UL;
- if (current->flags & PF_RANDOMIZE) {
- random_factor = get_random_int();
- random_factor = random_factor << PAGE_SHIFT;
- if (TASK_IS_32BIT_ADDR)
- random_factor &= 0xfffffful;
- else
- random_factor &= 0xffffffful;
- }
+ if (current->flags & PF_RANDOMIZE)
+ random_factor = mmap_rnd();
if (mmap_is_legacy()) {
mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
--
2.7.4
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