3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

[ 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 <casca...@canonical.com>
Reviewed-by: Sabrina Dubroca <s...@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klass...@secunet.com>
Signed-off-by: Sasha Levin <sas...@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 ca3f29b98ae5..63724226042c 100644
--- a/net/ipv6/xfrm6_output.c
+++ b/net/ipv6/xfrm6_output.c
@@ -151,9 +151,11 @@ static int __xfrm6_output(struct sk_buff *skb)
 
        if (skb->len > mtu && xfrm6_local_dontfrag(skb)) {
                xfrm6_local_rxpmtu(skb, mtu);
+               kfree_skb(skb);
                return -EMSGSIZE;
        } else if (!skb->ignore_df && skb->len > mtu && skb->sk) {
                xfrm_local_error(skb, mtu);
+               kfree_skb(skb);
                return -EMSGSIZE;
        }
 
-- 
2.17.1



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