From: Alexandre Ghiti <[email protected]> [ Upstream commit e8d54b62c55ab6201de6d195fc2c276294c1f6ae ]
Do not offset mmap base address because of stack randomization if current task does not want randomization. Note that x86 already implements this behaviour. Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Alexandre Ghiti <[email protected]> Acked-by: Catalin Marinas <[email protected]> Acked-by: Kees Cook <[email protected]> Reviewed-by: Christoph Hellwig <[email protected]> Reviewed-by: Luis Chamberlain <[email protected]> Cc: Albert Ou <[email protected]> Cc: Alexander Viro <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: James Hogan <[email protected]> Cc: Palmer Dabbelt <[email protected]> Cc: Paul Burton <[email protected]> Cc: Ralf Baechle <[email protected]> Cc: Russell King <[email protected]> Cc: Will Deacon <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Sasha Levin <[email protected]> --- arch/arm64/mm/mmap.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c index b050641b51392..8dac7110f0cb5 100644 --- a/arch/arm64/mm/mmap.c +++ b/arch/arm64/mm/mmap.c @@ -54,7 +54,11 @@ unsigned long arch_mmap_rnd(void) static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) { unsigned long gap = rlim_stack->rlim_cur; - unsigned long pad = (STACK_RND_MASK << PAGE_SHIFT) + stack_guard_gap; + unsigned long pad = stack_guard_gap; + + /* Account for stack randomization if necessary */ + if (current->flags & PF_RANDOMIZE) + pad += (STACK_RND_MASK << PAGE_SHIFT); /* Values close to RLIM_INFINITY can overflow. */ if (gap + pad > gap) -- 2.20.1
