[PATCH v5 07/14] arm: Use STACK_TOP when computing mmap base address

[Alexandre Ghiti]

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 <a...@ghiti.fr>
Acked-by: Kees Cook <keesc...@chromium.org>
Reviewed-by: Luis Chamberlain <mcg...@kernel.org>
---
 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)
 #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