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Subject[PATCH 4.15 075/122] tcp: purge write queue upon RST
Date
4.15-stable review patch.  If anyone has any objections, please let me know.

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

From: Soheil Hassas Yeganeh <soheil@google.com>


[ Upstream commit a27fd7a8ed3856faaf5a2ff1c8c5f00c0667aaa0 ]

When the connection is reset, there is no point in
keeping the packets on the write queue until the connection
is closed.

RFC 793 (page 70) and RFC 793-bis (page 64) both suggest
purging the write queue upon RST:
https://tools.ietf.org/html/draft-ietf-tcpm-rfc793bis-07

Moreover, this is essential for a correct MSG_ZEROCOPY
implementation, because userspace cannot call close(fd)
before receiving zerocopy signals even when the connection
is reset.

Fixes: f214f915e7db ("tcp: enable MSG_ZEROCOPY")
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/tcp_input.c | 1 +
1 file changed, 1 insertion(+)

--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3988,6 +3988,7 @@ void tcp_reset(struct sock *sk)
/* This barrier is coupled with smp_rmb() in tcp_poll() */
smp_wmb();

+ tcp_write_queue_purge(sk);
tcp_done(sk);

if (!sock_flag(sk, SOCK_DEAD))

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