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From: linan666@huaweicloud.com
To: richard@nod.at,
	miquel.raynal@bootlin.com,
	vigneshr@ti.com,
	axboe@kernel.dk,
	chaitanya.kulkarni@wdc.com
Cc: linux-mtd@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	linan666@huaweicloud.com,
	yukuai3@huawei.com,
	yi.zhang@huawei.com,
	houtao1@huawei.com,
	yangerkun@huawei.com
Subject: [PATCH] ubi: block: fix null-pointer-dereference in ubiblock_create()
Date: Sun, 28 Apr 2024 15:19:22 +0800
Message-Id: <20240428071922.2270892-1-linan666@huaweicloud.com>
Precedence: bulk
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From: Li Nan <linan122@huawei.com>

Similar to commit adbf4c4954e3 ("ubi: block: fix memleak in
ubiblock_create()"), 'dev->gd' is not assigned but dereferenced if
blk_mq_alloc_tag_set() fails, and leading to a null-pointer-dereference.

Using 'gd' directly here is not a good idea, too. 'gd->part0.bd_device'
is not initialized at this point. The error log will be:
  block (null): block: dynamic minor allocation failed

Fix it by using pr_err() and print ubi id.

Fixes: 77567b25ab9f ("ubi: use blk_mq_alloc_disk and blk_cleanup_disk")
Signed-off-by: Li Nan <linan122@huawei.com>
---
 drivers/mtd/ubi/block.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
index f82e3423acb9..bf7308e8ec2f 100644
--- a/drivers/mtd/ubi/block.c
+++ b/drivers/mtd/ubi/block.c
@@ -390,7 +390,8 @@ int ubiblock_create(struct ubi_volume_info *vi)
 
 	ret = blk_mq_alloc_tag_set(&dev->tag_set);
 	if (ret) {
-		dev_err(disk_to_dev(dev->gd), "blk_mq_alloc_tag_set failed");
+		pr_err("ubiblock%d_%d: blk_mq_alloc_tag_set failed\n",
+			dev->ubi_num, dev->vol_id);
 		goto out_free_dev;
 	}
 
@@ -407,8 +408,8 @@ int ubiblock_create(struct ubi_volume_info *vi)
 	gd->minors = 1;
 	gd->first_minor = idr_alloc(&ubiblock_minor_idr, dev, 0, 0, GFP_KERNEL);
 	if (gd->first_minor < 0) {
-		dev_err(disk_to_dev(gd),
-			"block: dynamic minor allocation failed");
+		pr_err("ubiblock%d_%d: block: dynamic minor allocation failed\n",
+			dev->ubi_num, dev->vol_id);
 		ret = -ENODEV;
 		goto out_cleanup_disk;
 	}
-- 
2.39.2