| Message ID | 20190417052247.17809-4-alex@ghiti.fr (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Provide generic top-down mmap layout functions | expand |
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 >
On 4/18/19 12:37 AM, Kees Cook wrote: > 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? Ok I will add this in case of a v4. > >> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> > Acked-by: Kees Cook <keescook@chromium.org> Thanks ! > > -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 >> >
On Wed, Apr 17, 2019 at 01:22:39AM -0400, Alexandre Ghiti wrote: > Do not offset mmap base address because of stack randomization if > current task does not want randomization. > > Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> Looks good, Reviewed-by: Christoph Hellwig <hch@lst.de>
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)
Do not offset mmap base address because of stack randomization if current task does not want randomization. Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> --- arch/arm64/mm/mmap.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)