From 17f85d704d443611885daffc3f15076d9e3573cf Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 15 Feb 2019 13:36:21 -0800 Subject: [PATCH] tcp: tcp_v4_err() should be more careful [ Upstream commit 2c4cc9712364c051b1de2d175d5fbea6be948ebf ] ICMP handlers are not very often stressed, we should make them more resilient to bugs that might surface in the future. If there is no packet in retransmit queue, we should avoid a NULL deref. Signed-off-by: Eric Dumazet Reported-by: soukjin bae Acked-by: Neal Cardwell Acked-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_ipv4.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 3738778a3444..e6a22c25fabf 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -469,14 +469,15 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info) if (sock_owned_by_user(sk)) break; + skb = tcp_write_queue_head(sk); + if (WARN_ON_ONCE(!skb)) + break; + icsk->icsk_backoff--; icsk->icsk_rto = tp->srtt_us ? __tcp_set_rto(tp) : TCP_TIMEOUT_INIT; icsk->icsk_rto = inet_csk_rto_backoff(icsk, TCP_RTO_MAX); - skb = tcp_write_queue_head(sk); - BUG_ON(!skb); - remaining = icsk->icsk_rto - min(icsk->icsk_rto, tcp_time_stamp - tcp_skb_timestamp(skb));