tcp: exit if nothing to retransmit on RTO timeout

Previously TCP only warns if its RTO timer fires and the retransmission queue is empty, but it'll cause null pointer reference later on. It's better to avoid such catastrophic failure and simply exit with a warning. Signed-off-by: Yuchung Cheng <[email protected]> Signed-off-by: Eric Dumazet <[email protected]> Reviewed-by: Neal Cardwell <[email protected]> Reviewed-by: Soheil Hassas Yeganeh <[email protected]> Signed-off-by: David S. Miller <[email protected]>
blogic · Jan 17, 2019 · 88f8598 · 88f8598
1 parent 9b420ef
commit 88f8598
Showing 1 changed file with 2 additions and 4 deletions.
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
@@ -443,10 +443,8 @@ void tcp_retransmit_timer(struct sock *sk)
 		 */
 		return;
 	}
-	if (!tp->packets_out)
-		goto out;
-
-	WARN_ON(tcp_rtx_queue_empty(sk));
+	if (!tp->packets_out || WARN_ON_ONCE(tcp_rtx_queue_empty(sk)))
+		return;
 
 	tp->tlp_high_seq = 0;