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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>
This commit is contained in:
Eric Paris 2007-11-26 18:47:26 -05:00 committed by James Morris
parent ab5a91a836
commit 8869477a49
1 changed files with 6 additions and 2 deletions
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8
mm/mmap.c
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@ -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) {