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| author | Xin Long <lucien.xin@gmail.com> | 2020-07-07 02:02:32 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-07-08 15:24:33 -0700 |
| commit | 27d53323664c549b5bb2dfaaf6f7ad6e0376a64e (patch) | |
| tree | c5d8199ae8714311b5e28cd8d1415959607ea464 /net/l2tp/l2tp_core.c | |
| parent | 1412bb2b4bb7e05b694742748b0f315664d91450 (diff) | |
| download | linux-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/l2tp/l2tp_core.c')
| -rw-r--r-- | net/l2tp/l2tp_core.c | 5 |
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) { |