[PATCH AUTOSEL 4.4 02/25] xfrm6: call kfree_skb when skb is toobig

Sasha Levin
2018-10-16T04:15:43Z

From: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

[ Upstream commit 215ab0f021c9fea3c18b75e7d522400ee6a49990 ]

After commit d6990976af7c5d8f55903bfb4289b6fb030bf754 ("vti6: fix PMTU caching
and reporting on xmit"), some too big skbs might be potentially passed down to
__xfrm6_output, causing it to fail to transmit but not free the skb, causing a
leak of skb, and consequentially a leak of dst references.

After running pmtu.sh, that shows as failure to unregister devices in a namespace:

[ 311.397671] unregister_netdevice: waiting for veth_b to become free. Usage count = 1

The fix is to call kfree_skb in case of transmit failures.

Fixes: dd767856a36e ("xfrm6: Don't call icmpv6_send on local error")
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/ipv6/xfrm6_output.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/net/ipv6/xfrm6_output.c b/net/ipv6/xfrm6_output.c
index 4d09ce6fa90e..64862c5084ee 100644
--- a/net/ipv6/xfrm6_output.c
+++ b/net/ipv6/xfrm6_output.c
@@ -165,9 +165,11 @@ static int __xfrm6_output(struct net *net, struct sock *sk, struct sk_buff *skb)

if (toobig && xfrm6_local_dontfrag(skb)) {
xfrm6_local_rxpmtu(skb, mtu);
+ kfree_skb(skb);
return -EMSGSIZE;
} else if (!skb->ignore_df && toobig && skb->sk) {
xfrm_local_error(skb, mtu);
+ kfree_skb(skb);
return -EMSGSIZE;
}

--
2.17.1