Commit a3374c42 authored Oct 18, 2012 by Eric Dumazet Committed by David S. Miller Oct 18, 2012

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 <enh@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent c6846ee1

net/ipv4/tcp.c

+3 −5

Original line number	Diff line number	Diff line
		@@ -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);