The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 82dd0d2a9a76fc8fa2b18d80b987d455728bf83a Mon Sep 17 00:00:00 2001

From: David Ahern dsahern@gmail.com Date: Thu, 29 Mar 2018 12:49:52 -0700 Subject: [PATCH] vrf: Fix use after free and double free in vrf_finish_output

Miguel reported an skb use after free / double free in vrf_finish_output when neigh_output returns an error. The vrf driver should return after the call to neigh_output as it takes over the skb on error path as well.

Patch is a simplified version of Miguel's patch which was written for 4.9, and updated to top of tree.

Fixes: 8f58336d3f78a ("net: Add ethernet header for pass through VRF device") Signed-off-by: Miguel Fadon Perlines mfadon@teldat.com Signed-off-by: David Ahern dsahern@gmail.com Signed-off-by: David S. Miller davem@davemloft.net

diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c index 139c61c8244a..ac40924fe437 100644 --- a/drivers/net/vrf.c +++ b/drivers/net/vrf.c @@ -578,12 +578,13 @@ static int vrf_finish_output(struct net *net, struct sock *sk, struct sk_buff *s if (!IS_ERR(neigh)) { sock_confirm_neigh(skb, neigh); ret = neigh_output(neigh, skb); + rcu_read_unlock_bh(); + return ret; }

rcu_read_unlock_bh(); err: - if (unlikely(ret < 0)) - vrf_tx_error(skb->dev, skb); + vrf_tx_error(skb->dev, skb); return ret; }