[Qemu-devel] [PATCH] qcow2.c: Check if backing file name length is valid

[Deepak Kathayat]

Signed-off-by: Deepak Kathayat <address@hidden>
---
The len variable is a signed integer whereas the backing file name
 length in the image header is unsigned. Therefore, it may
 overflow. Furthermore, backing file name length cannot be
 zero. These two cases must be handled explicitly.
 block/qcow2.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/block/qcow2.c b/block/qcow2.c
index 945c9d6..7b6f65c 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -625,6 +625,11 @@ static int qcow2_open(BlockDriverState *bs, QDict 
*options, int flags,
     /* read the backing file name */
     if (header.backing_file_offset != 0) {
         len = header.backing_file_size;
+        if (len <= 0) {
+            error_setg(errp, "Invalid backing file name length: %d", len);
+            ret = -EINVAL;
+            goto fail;
+        }
         if (len > 1023) {
             len = 1023;
         }
-- 
1.7.9.5