51 lines
1.5 KiB
Diff
51 lines
1.5 KiB
Diff
From a626ca6a656450e9f4df91d0dda238fff23285f4 Mon Sep 17 00:00:00 2001
|
|
From: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Date: Wed, 13 Apr 2011 08:07:28 -0700
|
|
Subject: vm: fix vm_pgoff wrap in stack expansion
|
|
MIME-Version: 1.0
|
|
Content-Type: text/plain; charset=UTF-8
|
|
Content-Transfer-Encoding: 8bit
|
|
|
|
From: Linus Torvalds <torvalds@linux-foundation.org>
|
|
|
|
commit a626ca6a656450e9f4df91d0dda238fff23285f4 upstream.
|
|
|
|
Commit 982134ba6261 ("mm: avoid wrapping vm_pgoff in mremap()") fixed
|
|
the case of a expanding mapping causing vm_pgoff wrapping when you used
|
|
mremap. But there was another case where we expand mappings hiding in
|
|
plain sight: the automatic stack expansion.
|
|
|
|
This fixes that case too.
|
|
|
|
This one also found by Robert Święcki, using his nasty system call
|
|
fuzzer tool. Good job.
|
|
|
|
Reported-and-tested-by: Robert Święcki <robert@swiecki.net>
|
|
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
|
|
|
|
---
|
|
mm/mmap.c | 13 ++++++++-----
|
|
1 file changed, 8 insertions(+), 5 deletions(-)
|
|
|
|
--- a/mm/mmap.c
|
|
+++ b/mm/mmap.c
|
|
@@ -1814,10 +1814,13 @@ static int expand_downwards(struct vm_ar
|
|
size = vma->vm_end - address;
|
|
grow = (vma->vm_start - address) >> PAGE_SHIFT;
|
|
|
|
- error = acct_stack_growth(vma, size, grow);
|
|
- if (!error) {
|
|
- vma->vm_start = address;
|
|
- vma->vm_pgoff -= grow;
|
|
+ error = -ENOMEM;
|
|
+ if (grow <= vma->vm_pgoff) {
|
|
+ error = acct_stack_growth(vma, size, grow);
|
|
+ if (!error) {
|
|
+ vma->vm_start = address;
|
|
+ vma->vm_pgoff -= grow;
|
|
+ }
|
|
}
|
|
}
|
|
vma_unlock_anon_vma(vma);
|