xfrm6: call kfree_skb when skb is toobig

BugLink: https://bugs.launchpad.net/bugs/1836654
[ 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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/net/ipv6/xfrm6_output.c b/net/ipv6/xfrm6_output.c
index 8ae87d4ec5ff607d431513bb2ef42d5c2c93450a..29dae7f2ff14d7bd5c5932b752e72da02b5537ac 100644 (file)
--- 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;
        }