linux-kernel - [PATCH 4.7 033/184] tcp: fastopen: avoid negative sk_forward

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Date:   Thu, 22 Sep 2016 19:39:27 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
        Josh Hunt <johunt@...mai.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.7 033/184] tcp: fastopen: avoid negative sk_forward_alloc

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

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

From: Eric Dumazet <edumazet@...gle.com>


[ Upstream commit 76061f631c2ea4ab9c4d66f3a96ecc5737f5aaf7 ]

When DATA and/or FIN are carried in a SYN/ACK message or SYN message,
we append an skb in socket receive queue, but we forget to call
sk_forced_mem_schedule().

Effect is that the socket has a negative sk->sk_forward_alloc as long as
the message is not read by the application.

Josh Hunt fixed a similar issue in commit d22e15371811 ("tcp: fix tcp
fin memory accounting")

Fixes: 168a8f58059a ("tcp: TCP Fast Open Server - main code path")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Reviewed-by: Josh Hunt <johunt@...mai.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv4/tcp_fastopen.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -150,6 +150,7 @@ void tcp_fastopen_add_skb(struct sock *s
 	tp->segs_in = 0;
 	tcp_segs_in(tp, skb);
 	__skb_pull(skb, tcp_hdrlen(skb));
+	sk_forced_mem_schedule(sk, skb->truesize);
 	skb_set_owner_r(skb, sk);
 
 	TCP_SKB_CB(skb)->seq++;