linux-kernel - Re: [PATCH v3] ubi: block: fix null-pointer-dereference in ubiblock

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Date: Wed, 22 May 2024 17:22:03 +0800
From: Zhihao Cheng <chengzhihao1@...wei.com>
To: <linan666@...weicloud.com>, <richard@....at>, <miquel.raynal@...tlin.com>,
	<vigneshr@...com>, <chaitanya.kulkarni@....com>, <axboe@...nel.dk>
CC: <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	<yukuai3@...wei.com>, <yi.zhang@...wei.com>, <houtao1@...wei.com>,
	<yangerkun@...wei.com>
Subject: Re: [PATCH v3] ubi: block: fix null-pointer-dereference in
 ubiblock_create()

在 2024/5/23 1:10, linan666@...weicloud.com 写道:
> From: Li Nan <linan122@...wei.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.
> Fix it by using pr_err() and variable 'dev' to print error log.
> 
> Additionally, the log in the error handle path of idr_alloc() has
> been improved by using pr_err(), too. Before initializing device
> name, using dev_err() will print error log with 'null' instead of
> the actual device name, like this:
>    block (null): ...
>          ~~~~~~
> It is unclear. Using pr_err() can print more details of the device.
> The improved log is:
>    ubiblock0_0: ...
> 
> Fixes: 77567b25ab9f ("ubi: use blk_mq_alloc_disk and blk_cleanup_disk")
> Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
> Signed-off-by: Li Nan <linan122@...wei.com>
> ---
> v3: spliting this patch into two in v2 is not a good idea. This version
> is consistent with v1, but only optimizes the commit message.
> 
>   drivers/mtd/ubi/block.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)

Reviewed-by: Zhihao Cheng <chengzhihao1@...wei.com>
> 
> 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;
>   	}
>