Patchwork vm: fix vm_pgoff wrap in upward expansion

login
register
mail settings
Submitter Paolo Pisati
Date Oct. 12, 2011, 11:03 a.m.
Message ID <1318417391-5573-2-git-send-email-paolo.pisati@canonical.com>
Download mbox | patch
Permalink /patch/119182/
State New
Headers show

Comments

Paolo Pisati - Oct. 12, 2011, 11:03 a.m.
From: Hugh Dickins <hughd@google.com>

vm: fix vm_pgoff wrap in upward expansion

Commit a626ca6a6564 ("vm: fix vm_pgoff wrap in stack expansion") fixed
the case of an expanding mapping causing vm_pgoff wrapping when you had
downward stack expansion.  But there was another case where IA64 and
PA-RISC expand mappings: upward expansion.

This fixes that case too.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

CVE-2011-2496

BugLink: http://bugs.launchpad.net/bugs/869243

(cherry picked from commit 42c36f63ac1366ab0ecc2d5717821362c259f517)

Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
---
 mm/mmap.c |   11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)

Patch

diff --git a/mm/mmap.c b/mm/mmap.c
index 968c3e0..e9cc676 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1867,10 +1867,13 @@  int expand_upwards(struct vm_area_struct *vma, unsigned long address)
 		size = address - vma->vm_start;
 		grow = (address - vma->vm_end) >> PAGE_SHIFT;
 
-		error = acct_stack_growth(vma, size, grow);
-		if (!error) {
-			vma->vm_end = address;
-			perf_event_mmap(vma);
+		error = -ENOMEM;
+		if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
+			error = acct_stack_growth(vma, size, grow);
+			if (!error) {
+				vma->vm_end = address;
+				perf_event_mmap(vma);
+			}
 		}
 	}
 	vma_unlock_anon_vma(vma);