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Subject[PATCH AUTOSEL 4.18 002/100] xfrm6: call kfree_skb when skb is toobig
From: Thadeu Lima de Souza Cascardo <>

[ 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, 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 <>
Reviewed-by: Sabrina Dubroca <>
Signed-off-by: Steffen Klassert <>
Signed-off-by: Sasha Levin <>
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 5959ce9620eb..6a74080005cf 100644
--- a/net/ipv6/xfrm6_output.c
+++ b/net/ipv6/xfrm6_output.c
@@ -170,9 +170,11 @@ 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;

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