On Wed, Apr 17, 2019 at 12:29 AM Alexandre Ghiti <alex@xxxxxxxx> wrote: > > mmap base address must be computed wrt stack top address, using TASK_SIZE > is wrong since STACK_TOP and TASK_SIZE are not equivalent. > > Signed-off-by: Alexandre Ghiti <alex@xxxxxxxx> > --- > arch/arm/mm/mmap.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c > index bff3d00bda5b..0b94b674aa91 100644 > --- a/arch/arm/mm/mmap.c > +++ b/arch/arm/mm/mmap.c > @@ -19,7 +19,7 @@ > > /* gap between mmap and stack */ > #define MIN_GAP (128*1024*1024UL) > -#define MAX_GAP ((TASK_SIZE)/6*5) > +#define MAX_GAP ((STACK_TOP)/6*5) Parens around STACK_TOP aren't needed, but you'll be removing it entirely, so I can't complain. ;) > #define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) > > static int mmap_is_legacy(struct rlimit *rlim_stack) > @@ -51,7 +51,7 @@ static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) > else if (gap > MAX_GAP) > gap = MAX_GAP; > > - return PAGE_ALIGN(TASK_SIZE - gap - rnd); > + return PAGE_ALIGN(STACK_TOP - gap - rnd); > } > > /* > -- > 2.20.1 > Acked-by: Kees Cook <keescook@xxxxxxxxxxxx> -- Kees Cook
