Re: [PATCH v3] ubi: block: fix null-pointer-dereference in ubiblock_create()

[Daniel Golle]

On Thu, May 23, 2024 at 01:10:35AM +0800, linan666@xxxxxxxxxxxxxxx wrote:
> From: Li Nan <linan122@xxxxxxxxxx>
> 
> 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@xxxxxxxxxx>
> Signed-off-by: Li Nan <linan122@xxxxxxxxxx>

Reviewed-by: Daniel Golle <daniel@xxxxxxxxxxxxxx>

> ---
> 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(-)
> 
> 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
> 
> 
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