Messages in this thread | | | From | Kees Cook <> | Date | Wed, 17 Apr 2019 23:37:00 -0500 | Subject | Re: [PATCH v3 03/11] arm64: Consider stack randomization for mmap base only when necessary |
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On Wed, Apr 17, 2019 at 12:26 AM Alexandre Ghiti <alex@ghiti.fr> wrote: > > Do not offset mmap base address because of stack randomization if > current task does not want randomization.
Maybe mention that this makes this logic match the existing x86 behavior too?
> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Acked-by: Kees Cook <keescook@chromium.org>
-Kees
> --- > 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 ed4f9915f2b8..ac89686c4af8 100644 > --- a/arch/arm64/mm/mmap.c > +++ b/arch/arm64/mm/mmap.c > @@ -65,7 +65,11 @@ 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 >
-- Kees Cook
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