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s390/mmap: randomize mmap base for bottom up direction

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Implement mmap base randomization for the bottom up direction, so ASLR
works for both mmap layouts on s390.  See also commit df54d6fa5427 ("x86
get_unmapped_area(): use proper mmap base for bottom-up direction").

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Radu Caragea <sinaelgl@gmail.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Heiko Carstens 2013-11-12 15:07:55 -08:00 committed by Linus Torvalds
parent 4e99b02131
commit 7aba842f08
1 changed files with 7 additions and 2 deletions
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9
arch/s390/mm/mmap.c
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@ -64,6 +64,11 @@ static unsigned long mmap_rnd(void)
return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
}
static unsigned long mmap_base_legacy(void)
{
return TASK_UNMAPPED_BASE + mmap_rnd();
}
static inline unsigned long mmap_base(void)
{
unsigned long gap = rlimit(RLIMIT_STACK);
@ -89,7 +94,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
* bit is set, or if the expected stack growth is unlimited:
*/
if (mmap_is_legacy()) {
mm->mmap_base = TASK_UNMAPPED_BASE;
mm->mmap_base = mmap_base_legacy();
mm->get_unmapped_area = arch_get_unmapped_area;
} else {
mm->mmap_base = mmap_base();
@ -164,7 +169,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
* bit is set, or if the expected stack growth is unlimited:
*/
if (mmap_is_legacy()) {
mm->mmap_base = TASK_UNMAPPED_BASE;
mm->mmap_base = mmap_base_legacy();
mm->get_unmapped_area = s390_get_unmapped_area;
} else {
mm->mmap_base = mmap_base();