From: Alexandre Ghiti <a...@ghiti.fr> [ 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/20190730055113.23635-4-a...@ghiti.fr Signed-off-by: Alexandre Ghiti <a...@ghiti.fr> Acked-by: Catalin Marinas <catalin.mari...@arm.com> Acked-by: Kees Cook <keesc...@chromium.org> Reviewed-by: Christoph Hellwig <h...@lst.de> Reviewed-by: Luis Chamberlain <mcg...@kernel.org> Cc: Albert Ou <a...@eecs.berkeley.edu> Cc: Alexander Viro <v...@zeniv.linux.org.uk> Cc: Christoph Hellwig <h...@infradead.org> Cc: James Hogan <jho...@kernel.org> Cc: Palmer Dabbelt <pal...@sifive.com> Cc: Paul Burton <paul.bur...@mips.com> Cc: Ralf Baechle <r...@linux-mips.org> Cc: Russell King <li...@armlinux.org.uk> Cc: Will Deacon <will.dea...@arm.com> Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Sasha Levin <sas...@kernel.org> --- 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
