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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        "Nicolas Dichtel" <nicolas.dichtel@6wind.com>,
        "David S. Miller" <davem@davemloft.net>,
        "Ben Hutchings" <ben.hutchings@codethink.co.uk>
Date:   Thu, 07 Jun 2018 15:05:21 +0100
Message-ID: <lsq.1528380321.927342213@decadent.org.uk>
Subject: [PATCH 3.16 221/410] netlink: avoid a double skb free in
 genlmsg_mcast()
In-Reply-To: <lsq.1528380320.647747352@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

3.16.57-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Nicolas Dichtel <nicolas.dichtel@6wind.com>

commit 02a2385f37a7c6594c9d89b64c4a1451276f08eb upstream.

nlmsg_multicast() consumes always the skb, thus the original skb must be
freed only when this function is called with a clone.

Fixes: cb9f7a9a5c96 ("netlink: ensure to loop over all netns in genlmsg_multicast_allns()")
Reported-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 net/netlink/genetlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -1067,7 +1067,7 @@ static int genlmsg_mcast(struct sk_buff
 	if (!err)
 		delivered = true;
 	else if (err != -ESRCH)
-		goto error;
+		return err;
 	return delivered ? 0 : -ESRCH;
  error:
 	kfree_skb(skb);