Commit e8d54b62 authored by Alexandre Ghiti's avatar Alexandre Ghiti Committed by Linus Torvalds

arm64: consider stack randomization for mmap base only when necessary

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-alex@ghiti.frSigned-off-by: default avatarAlexandre Ghiti <alex@ghiti.fr>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 28058ed6
...@@ -54,7 +54,11 @@ unsigned long arch_mmap_rnd(void) ...@@ -54,7 +54,11 @@ unsigned long arch_mmap_rnd(void)
static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
{ {
unsigned long gap = rlim_stack->rlim_cur; 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. */ /* Values close to RLIM_INFINITY can overflow. */
if (gap + pad > gap) if (gap + pad > gap)
......
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