qcow2: Fix new L1 table size check (CVE-2014-0143)

The size in bytes is assigned to an int later, so check that instead of
the number of entries.

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 cab60de)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

block/qcow2-cluster.c

@@ -55,7 +55,7 @@ int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
         }
     }
 
-    if (new_l1_size > INT_MAX) {
+    if (new_l1_size > INT_MAX / sizeof(uint64_t)) {
         return -EFBIG;
     }