linux-kernel - [PATCH 4.14 113/138] vrf: Fix use after free and double free in vrf_finish

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Date:   Wed, 11 Apr 2018 00:25:03 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Miguel Fadon Perlines <mfadon@...dat.com>,
        David Ahern <dsahern@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.14 113/138] vrf: Fix use after free and double free in vrf_finish_output

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

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

From: David Ahern <dsahern@...il.com>


[ Upstream commit 82dd0d2a9a76fc8fa2b18d80b987d455728bf83a ]

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@...dat.com>
Signed-off-by: David Ahern <dsahern@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/vrf.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/net/vrf.c
+++ b/drivers/net/vrf.c
@@ -579,12 +579,13 @@ static int vrf_finish_output(struct net
 	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;
 }