rdma: validate RDMAControlHeader::len

RMDAControlHeader::len is provided from remote, so validate it.
Reviewed-by: NOrit Wasserman <owasserm@redhat.com>
Reviewed-by: NMichael R. Hines <mrhines@us.ibm.com>
Signed-off-by: NIsaku Yamahata <yamahata@private.email.ne.jp>
Signed-off-by: NMichael R. Hines <mrhines@us.ibm.com>
Message-id: 1376078746-24948-3-git-send-email-mrhines@linux.vnet.ibm.com
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

migration-rdma.c

@@ -1424,6 +1424,7 @@ static int qemu_rdma_post_send_control(RDMAContext *rdma, uint8_t *buf,
      * The copy makes the RDMAControlHeader simpler to manipulate
      * for the time being.
      */
+    assert(head->len <= RDMA_CONTROL_MAX_BUFFER - sizeof(*head));
     memcpy(wr->control, head, sizeof(RDMAControlHeader));
     control_to_network((void *) wr->control);
 
@@ -1504,6 +1505,10 @@ static int qemu_rdma_exchange_get_response(RDMAContext *rdma,
                 control_desc[head->type], head->type, head->len);
         return -EIO;
     }
+    if (head->len > RDMA_CONTROL_MAX_BUFFER - sizeof(*head)) {
+        fprintf(stderr, "too long length: %d\n", head->len);
+        return -EINVAL;
+    }
 
     return 0;
 }