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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, Helen Koike <helen.koike@collabora.com>,
        Mike Snitzer <snitzer@redhat.com>
Subject: [PATCH 5.1 108/122] dm ioctl: fix hang in early create error condition
Date:   Thu, 23 May 2019 21:07:10 +0200
Message-Id: <20190523181719.695301559@linuxfoundation.org>
In-Reply-To: <20190523181705.091418060@linuxfoundation.org>
References: <20190523181705.091418060@linuxfoundation.org>
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From: Helen Koike <helen.koike@collabora.com>

commit 0f41fcf78849c902ddca564f99a8e23ccfc80333 upstream.

The dm_early_create() function (which deals with "dm-mod.create=" kernel
command line option) calls dm_hash_insert() who gets an extra reference
to the md object.

In case of failure, this reference wasn't being released, causing
dm_destroy() to hang, thus hanging the whole boot process.

Fix this by calling __hash_remove() in the error path.

Fixes: 6bbc923dfcf57d ("dm: add support to directly boot to a mapped device")
Cc: stable@vger.kernel.org
Signed-off-by: Helen Koike <helen.koike@collabora.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/md/dm-ioctl.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -2069,7 +2069,7 @@ int __init dm_early_create(struct dm_ioc
 	/* alloc table */
 	r = dm_table_create(&t, get_mode(dmi), dmi->target_count, md);
 	if (r)
-		goto err_destroy_dm;
+		goto err_hash_remove;
 
 	/* add targets */
 	for (i = 0; i < dmi->target_count; i++) {
@@ -2116,6 +2116,10 @@ int __init dm_early_create(struct dm_ioc
 
 err_destroy_table:
 	dm_table_destroy(t);
+err_hash_remove:
+	(void) __hash_remove(__get_name_cell(dmi->name));
+	/* release reference from __get_name_cell */
+	dm_put(md);
 err_destroy_dm:
 	dm_put(md);
 	dm_destroy(md);