qed: check for header size overflow

Header size is denoted in clusters.  The maximum cluster size is 64 MB
but there is no limit on header size.  Check for uint32_t overflow in
case the header size field has a whacky value.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1421065893-18875-2-git-send-email-stefanha@redhat.com
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/block/qed.c b/block/qed.c
index 80f18d82e2f606ec95da0015fbfdb2d6fa0ff042..892b13c80649cd8211d046c56f92336a54919818 100644 (file)
--- a/block/qed.c
+++ b/block/qed.c
@@ -440,6 +440,11 @@ static int bdrv_qed_open(BlockDriverState *bs, QDict *options, int flags,
     s->l2_mask = s->table_nelems - 1;
     s->l1_shift = s->l2_shift + ffs(s->table_nelems) - 1;
 
+    /* Header size calculation must not overflow uint32_t */
+    if (s->header.header_size > UINT32_MAX / s->header.cluster_size) {
+        return -EINVAL;
+    }
+
     if ((s->header.features & QED_F_BACKING_FILE)) {
         if ((uint64_t)s->header.backing_filename_offset +
             s->header.backing_filename_size >