netdev - [PATCH] netfilter: nfnetlink: fix potential dead lock in nfnetlink_rcv

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Date:   Thu, 3 Nov 2022 09:12:02 +0800
From:   Ziyang Xuan <william.xuanziyang@...wei.com>
To:     <pablo@...filter.org>, <kadlec@...filter.org>, <fw@...len.de>,
        <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <netfilter-devel@...r.kernel.org>
CC:     <coreteam@...filter.org>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] netfilter: nfnetlink: fix potential dead lock in nfnetlink_rcv_msg()

When type is NFNL_CB_MUTEX and -EAGAIN error occur in nfnetlink_rcv_msg(),
it does not execute nfnl_unlock(). That would trigger potential dead lock.

Fixes: 50f2db9e368f ("netfilter: nfnetlink: consolidate callback types")
Signed-off-by: Ziyang Xuan <william.xuanziyang@...wei.com>
---
 net/netfilter/nfnetlink.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 9c44518cb70f..6d18fb346868 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -294,6 +294,7 @@ static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 			nfnl_lock(subsys_id);
 			if (nfnl_dereference_protected(subsys_id) != ss ||
 			    nfnetlink_find_client(type, ss) != nc) {
+				nfnl_unlock(subsys_id);
 				err = -EAGAIN;
 				break;
 			}
-- 
2.25.1