On 4/18/19 1:27 AM, Kees Cook wrote:
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>
Thanks !
