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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 Williams <dan.j.williams@intel.com>,
        Christoph Hellwig <hch@lst.de>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 638/846] dm: fix alloc_dax error handling in alloc_dev
Date:   Mon, 24 Jan 2022 19:42:35 +0100
Message-Id: <20220124184123.035154111@linuxfoundation.org>
In-Reply-To: <20220124184100.867127425@linuxfoundation.org>
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From: Christoph Hellwig <hch@lst.de>

[ Upstream commit d751939235b9b7bc4af15f90a3e99288a8b844a7 ]

Make sure ->dax_dev is NULL on error so that the cleanup path doesn't
trip over an ERR_PTR.

Reported-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211129102203.2243509-2-hch@lst.de
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/md/dm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 76d9da49fda75..671bb454f1649 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1794,8 +1794,10 @@ static struct mapped_device *alloc_dev(int minor)
 	if (IS_ENABLED(CONFIG_DAX_DRIVER)) {
 		md->dax_dev = alloc_dax(md, md->disk->disk_name,
 					&dm_dax_ops, 0);
-		if (IS_ERR(md->dax_dev))
+		if (IS_ERR(md->dax_dev)) {
+			md->dax_dev = NULL;
 			goto bad;
+		}
 	}
 
 	format_dev_t(md->name, MKDEV(_major, minor));
-- 
2.34.1