From: Kevin Wolf <kwolf@redhat.com>
Date: Wed, 26 Mar 2014 13:05:42 +0100
Subject: qcow2: Check backing_file_offset (CVE-2014-0144)

Header, header extension and the backing file name must all be stored in
the first cluster. Setting the backing file to a much higher value
allowed header extensions to become much bigger than we want them to be
(unbounded allocation).

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit a1b3955c9415b1e767c130a2f59fee6aa28e575b)

Conflicts:
	tests/qemu-iotests/080
	tests/qemu-iotests/080.out

diff --git a/block/qcow2.c b/block/qcow2.c
index c1e0529..58902ca 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -302,6 +302,12 @@ static int qcow2_open(BlockDriverState *bs, int flags)
         }
     }
 
+    if (header.backing_file_offset > s->cluster_size) {
+        report_unsupported(bs, "Invalid backing file offset");
+        ret = -EINVAL;
+        goto fail;
+    }
+
     if (header.backing_file_offset) {
         ext_end = header.backing_file_offset;
     } else {
-- 
1.7.10.4