From 88f8598d0a302a08380eadefd09b9f5cb1c4c428 Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Wed, 16 Jan 2019 15:05:28 -0800 Subject: [PATCH] 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 Signed-off-by: Eric Dumazet Reviewed-by: Neal Cardwell Reviewed-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller --- net/ipv4/tcp_timer.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index 71a29e9c0620..e7d09e3705b8 100644 --- 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; -- 2.30.2