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cherry-pick tcp reset bug fix

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This commit is contained in:
Fabian Grünbichler 2017-09-18 10:38:27 +02:00
parent d799ad3bc2
commit 6029760ee4
2 changed files with 44 additions and 0 deletions
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43
0001-tcp-reset-sk_rx_dst-in-tcp_disconnect.patch Normal file
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@ -0,0 +1,43 @@
From d747a7a51b00984127a88113cdbbc26f91e9d815 Mon Sep 17 00:00:00 2001
From: WANG Cong <xiyou.wangcong@gmail.com>
Date: Sat, 24 Jun 2017 23:50:30 -0700
Subject: [PATCH] tcp: reset sk_rx_dst in tcp_disconnect()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
We have to reset the sk->sk_rx_dst when we disconnect a TCP
connection, because otherwise when we re-connect it this
dst reference is simply overridden in tcp_finish_connect().
This fixes a dst leak which leads to a loopback dev refcnt
leak. It is a long-standing bug, Kevin reported a very similar
(if not same) bug before. Thanks to Andrei for providing such
a reliable reproducer which greatly narrows down the problem.
Fixes: 41063e9dd119 ("ipv4: Early TCP socket demux.")
Reported-by: Andrei Vagin <avagin@gmail.com>
Reported-by: Kevin Xu <kaiwen.xu@hulu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
---
net/ipv4/tcp.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index b5ea036ca781..40aca7803cf2 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2330,6 +2330,8 @@ int tcp_disconnect(struct sock *sk, int flags)
tcp_init_send_head(sk);
memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
__sk_dst_reset(sk);
+ dst_release(sk->sk_rx_dst);
+ sk->sk_rx_dst = NULL;
tcp_saved_syn_free(tp);
/* Clean up fastopen related fields */
--
2.11.0

1
Makefile
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@ -246,6 +246,7 @@ ${KERNEL_SRC}/README: ${KERNEL_SRC_SUBMODULE} | submodules
cd ${KERNEL_SRC}; patch -p1 < ../cgroup-cpuset-add-cpuset.remap_cpus.patch
cd ${KERNEL_SRC}; patch -p1 < ../0001-netfilter-nft_set_rbtree-handle-re-addition-element-.patch # DoS from within (unpriv) containers
cd ${KERNEL_SRC}; patch -p1 < ../0001-block-fix-bio_will_gap-for-first-bvec-with-offset.patch
cd ${KERNEL_SRC}; patch -p1 < ../0001-tcp-reset-sk_rx_dst-in-tcp_disconnect.patch
sed -i ${KERNEL_SRC}/Makefile -e 's/^EXTRAVERSION.*$$/EXTRAVERSION=${EXTRAVERSION}/'
touch $@