From 1f0569df0b0285e7ec2432d804a4921b06a61618 Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Tue, 14 Apr 2015 15:47:51 -0700
Subject: [PATCH] mips: extract logic for mmap_rnd()
In preparation for splitting out ET_DYN ASLR, extract the mmap ASLR
selection into a separate function.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
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 f1baadd56e82e..9a4f1f5c1f0ea 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;
--
2.30.2