[PATCH 3.10 13/55] tcp: fix tcp fin memory accounting

From: Greg Kroah-Hartman
Date: Tue Mar 24 2015 - 11:45:01 EST


3.10-stable review patch. If anyone has any objections, please let me know.

------------------

From: Josh Hunt <johunt@xxxxxxxxxx>

[ 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@xxxxxxxxxx>

Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/tcp_output.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

--- 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);


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