From a3374c42aa5f7237e87ff3b0622018636b0c847e Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 18 Oct 2012 09:14:12 +0000 Subject: [PATCH] tcp: fix FIONREAD/SIOCINQ tcp_ioctl() tries to take into account if tcp socket received a FIN to report correct number bytes in receive queue. But its flaky because if the application ate the last skb, we return 1 instead of 0. Correct way to detect that FIN was received is to test SOCK_DONE. Reported-by: Elliot Hughes Signed-off-by: Eric Dumazet Cc: Neal Cardwell Cc: Tom Herbert Signed-off-by: David S. Miller --- net/ipv4/tcp.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index f32c02e2a543..b7c2f439b54f 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -549,14 +549,12 @@ int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg) !tp->urg_data || before(tp->urg_seq, tp->copied_seq) || !before(tp->urg_seq, tp->rcv_nxt)) { - struct sk_buff *skb; answ = tp->rcv_nxt - tp->copied_seq; - /* Subtract 1, if FIN is in queue. */ - skb = skb_peek_tail(&sk->sk_receive_queue); - if (answ && skb) - answ -= tcp_hdr(skb)->fin; + /* Subtract 1, if FIN was received */ + if (answ && sock_flag(sk, SOCK_DONE)) + answ--; } else answ = tp->urg_seq - tp->copied_seq; release_sock(sk); -- 2.20.1