From 8869477a49c3e99def1fcdadd6bbc407fea14b45 Mon Sep 17 00:00:00 2001
From: Eric Paris <eparis@redhat.com>
Date: Mon, 26 Nov 2007 18:47:26 -0500
Subject: [PATCH] security: protect from stack expantion into low vm addresses
Add security checks to make sure we are not attempting to expand the
stack into memory protected by mmap_min_addr
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
---
mm/mmap.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index facc1a75bd4fd..938313c76d02f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1615,6 +1615,12 @@ static inline int expand_downwards(struct vm_area_struct *vma,
*/
if (unlikely(anon_vma_prepare(vma)))
return -ENOMEM;
+
+ address &= PAGE_MASK;
+ error = security_file_mmap(0, 0, 0, 0, address, 1);
+ if (error)
+ return error;
+
anon_vma_lock(vma);
/*
@@ -1622,8 +1628,6 @@ static inline int expand_downwards(struct vm_area_struct *vma,
* is required to hold the mmap_sem in read mode. We need the
* anon_vma lock to serialize against concurrent expand_stacks.
*/
- address &= PAGE_MASK;
- error = 0;
/* Somebody else might have raced and expanded it already */
if (address < vma->vm_start) {
--
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