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authorXin Long <lucien.xin@gmail.com>2020-07-07 02:02:32 +0800
committerDavid S. Miller <davem@davemloft.net>2020-07-08 15:24:33 -0700
commit27d53323664c549b5bb2dfaaf6f7ad6e0376a64e (patch)
treec5d8199ae8714311b5e28cd8d1415959607ea464 /net
parent1412bb2b4bb7e05b694742748b0f315664d91450 (diff)
downloadlinux-27d53323664c549b5bb2dfaaf6f7ad6e0376a64e.tar.bz2
l2tp: remove skb_dst_set() from l2tp_xmit_skb()
In the tx path of l2tp, l2tp_xmit_skb() calls skb_dst_set() to set skb's dst. However, it will eventually call inet6_csk_xmit() or ip_queue_xmit() where skb's dst will be overwritten by: skb_dst_set_noref(skb, dst); without releasing the old dst in skb. Then it causes dst/dev refcnt leak: unregister_netdevice: waiting for eth0 to become free. Usage count = 1 This can be reproduced by simply running: # modprobe l2tp_eth && modprobe l2tp_ip # sh ./tools/testing/selftests/net/l2tp.sh So before going to inet6_csk_xmit() or ip_queue_xmit(), skb's dst should be dropped. This patch is to fix it by removing skb_dst_set() from l2tp_xmit_skb() and moving skb_dst_drop() into l2tp_xmit_core(). Fixes: 3557baabf280 ("[L2TP]: PPP over L2TP driver core") Reported-by: Hangbin Liu <liuhangbin@gmail.com> Signed-off-by: Xin Long <lucien.xin@gmail.com> Acked-by: James Chapman <jchapman@katalix.com> Tested-by: James Chapman <jchapman@katalix.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/l2tp/l2tp_core.c5
1 files changed, 1 insertions, 4 deletions
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 6d7ef78c88af..6434d17e6e8e 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -1028,6 +1028,7 @@ static void l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
/* Queue the packet to IP for output */
skb->ignore_df = 1;
+ skb_dst_drop(skb);
#if IS_ENABLED(CONFIG_IPV6)
if (l2tp_sk_is_v6(tunnel->sock))
error = inet6_csk_xmit(tunnel->sock, skb, NULL);
@@ -1099,10 +1100,6 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len
goto out_unlock;
}
- /* Get routing info from the tunnel socket */
- skb_dst_drop(skb);
- skb_dst_set(skb, sk_dst_check(sk, 0));
-
inet = inet_sk(sk);
fl = &inet->cork.fl;
switch (tunnel->encap) {