Merge fix/hv_sock_eio/6.18 into v6.18.26

* commit 'e256ef5ed9ce517323be79ad3268ec698533dca3':
  hv_sock: Return -EIO for malformed/short packets
  hv_sock: Report EOF instead of -EIO for FIN

Author: chessturo

net/vmw_vsock/hyperv_transport.c

@@ -694,17 +694,38 @@ static ssize_t hvs_stream_enqueue(struct vsock_sock *vsk, struct msghdr *msg,
 static s64 hvs_stream_has_data(struct vsock_sock *vsk)
 {
 	struct hvsock *hvs = vsk->trans;
-	bool need_refill;
 	s64 ret;
 
 	if (hvs->recv_data_len > 0)
 		return hvs->recv_data_len;
 
 	switch (hvs_channel_readable_payload(hvs->chan)) {
 	case 1:
-		need_refill = !hvs->recv_desc;
-		if (!need_refill)
-			return -EIO;
+		if (hvs->recv_desc) {
+			/* Here hvs->recv_data_len is 0, so hvs->recv_desc must
+			 * be NULL unless it points to the 0-byte-payload FIN
+			 * packet or a malformed/short packet: see
+			 * hvs_update_recv_data().
+			 *
+			 * If hvs->recv_desc points to the FIN packet, here all
+			 * the payload has been dequeued and the peer_shutdown
+			 * flag is set, but hvs_channel_readable_payload() still
+			 * returns 1, because the VMBus ringbuffer's read_index
+			 * is not updated for the FIN packet:
+			 * hvs_stream_dequeue() -> hv_pkt_iter_next() updates
+			 * the cached priv_read_index but has no opportunity to
+			 * update the read_index in hv_pkt_iter_close() as
+			 * hvs_stream_has_data() returns 0 for the FIN packet,
+			 * so it won't get dequeued.
+			 *
+			 * In case hvs->recv_desc points to a malformed/short
+			 * packet, return -EIO.
+			 */
+			if (!(vsk->peer_shutdown & SEND_SHUTDOWN))
+				return -EIO;
+
+			return 0;
+		}
 
 		hvs->recv_desc = hv_pkt_iter_first(hvs->chan);
 		if (!hvs->recv_desc)