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mips: extract logic for mmap_rnd()

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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>
This commit is contained in:
Kees Cook 2015-04-14 15:47:51 -07:00 committed by Linus Torvalds
parent dd04cff1dc
commit 1f0569df0b
1 changed files with 16 additions and 8 deletions
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24
arch/mips/mm/mmap.c
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@ -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;