linux-kernel - [PATCH 4.9 17/28] netlink: avoid a double skb free in genlmsg

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Message-Id: <20180329175735.374546334@linuxfoundation.org>
Date:   Thu, 29 Mar 2018 20:00:36 +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,
        Ben Hutchings <ben.hutchings@...ethink.co.uk>,
        Nicolas Dichtel <nicolas.dichtel@...nd.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.9 17/28] netlink: avoid a double skb free in genlmsg_mcast()

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

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

From: Nicolas Dichtel <nicolas.dichtel@...nd.com>


[ Upstream commit 02a2385f37a7c6594c9d89b64c4a1451276f08eb ]

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@...ethink.co.uk>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@...nd.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/netlink/genetlink.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -1128,7 +1128,7 @@ 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);