tcp: fix tcp fin memory accounting

[ Upstream commit d22e1537181188e5dc8cbc51451832625035bdc2 ]

tcp_send_fin() does not account for the memory it allocates properly, so
sk_forward_alloc can be negative in cases where we've sent a FIN:

ss example output (ss -amn | grep -B1 f4294):
tcp    FIN-WAIT-1 0      1            192.168.0.1:45520         192.0.2.1:8080
	skmem:(r0,rb87380,t0,tb87380,f4294966016,w1280,o0,bl0)
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 923146c4f007699d563fa71914808e4d2a1b3965..6b554c37e08beff4ed78e1d215c05355ec418a04 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2593,15 +2593,11 @@ void tcp_send_fin(struct sock *sk)
        } else {
                /* Socket is locked, keep trying until memory is available. */
                for (;;) {
-                       skb = alloc_skb_fclone(MAX_TCP_HEADER,
-                                              sk->sk_allocation);
+                       skb = sk_stream_alloc_skb(sk, 0, sk->sk_allocation);
                        if (skb)
                                break;
                        yield();
                }
-
-               /* Reserve space for headers and prepare control bits. */
-               skb_reserve(skb, MAX_TCP_HEADER);
                /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */
                tcp_init_nondata_skb(skb, tp->write_seq,
                                     TCPHDR_ACK | TCPHDR_FIN);