From 45e77d314585869dfe43c82679f7e08c9b35b898 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Mon, 19 Jul 2010 01:16:18 +0000 Subject: [PATCH] tcp: fix crash in tcp_xmit_retransmit_queue MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit It can happen that there are no packets in queue while calling tcp_xmit_retransmit_queue(). tcp_write_queue_head() then returns NULL and that gets deref'ed to get sacked into a local var. There is no work to do if no packets are outstanding so we just exit early. This oops was introduced by 08ebd1721ab8fd (tcp: remove tp->lost_out guard to make joining diff nicer). Signed-off-by: Ilpo Järvinen Reported-by: Lennart Schulte Tested-by: Lennart Schulte Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index b4ed957f201a..7ed9dc1042d1 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2208,6 +2208,9 @@ void tcp_xmit_retransmit_queue(struct sock *sk) int mib_idx; int fwd_rexmitting = 0; + if (!tp->packets_out) + return; + if (!tp->lost_out) tp->retransmit_high = tp->snd_una;