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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dan Carpenter <dan.carpenter@oracle.com>,
        Goldwyn Rodrigues <rgoldwyn@suse.com>,
        Guoqing Jiang <gqjiang@suse.com>, Shaohua Li <shli@fb.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.9 087/310] md-cluster: fix potential lock issue in add_new_disk
Date:   Wed, 11 Apr 2018 20:33:46 +0200
Message-Id: <20180411183626.008481882@linuxfoundation.org>
In-Reply-To: <20180411183622.305902791@linuxfoundation.org>
References: <20180411183622.305902791@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Guoqing Jiang <gqjiang@suse.com>


[ Upstream commit 2dffdc0724004f38f5e39907747b53e4b0d80e59 ]

The add_new_disk returns with communication locked if
__sendmsg returns failure, fix it with call unlock_comm
before return.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
CC: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/md/md-cluster.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/md/md-cluster.c
+++ b/drivers/md/md-cluster.c
@@ -1122,8 +1122,10 @@ static int add_new_disk(struct mddev *md
 	cmsg.raid_slot = cpu_to_le32(rdev->desc_nr);
 	lock_comm(cinfo);
 	ret = __sendmsg(cinfo, &cmsg);
-	if (ret)
+	if (ret) {
+		unlock_comm(cinfo);
 		return ret;
+	}
 	cinfo->no_new_dev_lockres->flags |= DLM_LKF_NOQUEUE;
 	ret = dlm_lock_sync(cinfo->no_new_dev_lockres, DLM_LOCK_EX);
 	cinfo->no_new_dev_lockres->flags &= ~DLM_LKF_NOQUEUE;