From 142a2e7ece8d8ac0e818eb2c91f99ca894730e2a Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 26 Nov 2015 08:18:14 -0800 Subject: [PATCH] tcp: initialize tp->copied_seq in case of cross SYN connection Dmitry provided a syzkaller (http://github.com/google/syzkaller) generated program that triggers the WARNING at net/ipv4/tcp.c:1729 in tcp_recvmsg() : WARN_ON(tp->copied_seq != tp->rcv_nxt && !(flags & (MSG_PEEK | MSG_TRUNC))); His program is specifically attempting a Cross SYN TCP exchange, that we support (for the pleasure of hackers ?), but it looks we lack proper tcp->copied_seq initialization. Thanks again Dmitry for your report and testings. Signed-off-by: Eric Dumazet Reported-by: Dmitry Vyukov Tested-by: Dmitry Vyukov Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index a4a0b6b3bcf2..2d656eef7f8e 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5683,6 +5683,7 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb, } tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1; + tp->copied_seq = tp->rcv_nxt; tp->rcv_wup = TCP_SKB_CB(skb)->seq + 1; /* RFC1323: The window in SYN & SYN/ACK segments is -- 2.45.2