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Commit 7aba842f authored by Heiko Carstens's avatar Heiko Carstens Committed by Linus Torvalds
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s390/mmap: randomize mmap base for bottom up direction 



Implement mmap base randomization for the bottom up direction, so ASLR
works for both mmap layouts on s390.  See also commit df54d6fa ("x86
get_unmapped_area(): use proper mmap base for bottom-up direction").

Signed-off-by: default avatarHeiko 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4e99b021

arch/s390/mm/mmap.c

+7 −2
Original line number Diff line number Diff line
@@ -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();