From 9b61a4d1b2064dbd0c9e61754305ac852170509f Mon Sep 17 00:00:00 2001 From: Russell King Date: Wed, 16 May 2012 15:19:20 +0100 Subject: [PATCH] ARM: prevent VM_GROWSDOWN mmaps extending below FIRST_USER_ADDRESS Cc: Reported-by: Al Viro Signed-off-by: Russell King --- arch/arm/mm/fault.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c index f07467533365..5bb48356d217 100644 --- a/arch/arm/mm/fault.c +++ b/arch/arm/mm/fault.c @@ -247,7 +247,9 @@ good_area: return handle_mm_fault(mm, vma, addr & PAGE_MASK, flags); check_stack: - if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr)) + /* Don't allow expansion below FIRST_USER_ADDRESS */ + if (vma->vm_flags & VM_GROWSDOWN && + addr >= FIRST_USER_ADDRESS && !expand_stack(vma, addr)) goto good_area; out: return fault;