From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: [PATCH net] vrf: Fix use after free and double free in vrf_finish_output Date: Thu, 29 Mar 2018 12:49:52 -0700 Message-ID: <20180329194952.27097-1-dsahern@gmail.com> Cc: David Ahern , Miguel Fadon Perlines To: netdev@vger.kernel.org Return-path: Received: from mail-pf0-f196.google.com ([209.85.192.196]:39470 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751082AbeC2TuB (ORCPT ); Thu, 29 Mar 2018 15:50:01 -0400 Received: by mail-pf0-f196.google.com with SMTP id c78so3947786pfj.6 for ; Thu, 29 Mar 2018 12:50:01 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: 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 Signed-off-by: David Ahern --- drivers/net/vrf.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) 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; } -- 2.11.0