[v1] ubi: block: fix null-pointer-dereference in ubiblock_create()

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

Posted by linan666@huaweicloud.com 1 year, 7 months ago

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

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

Posted by Zhihao Cheng 1 year, 7 months ago

在 2024/4/28 15:19, linan666@huaweicloud.com 写道:
> 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);

There is no need to modify this place. The device of 'gd' is initialized 
in blk_mq_alloc_disk. Refer to nbd_dev_add.
>   	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;
>   	}
>

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

Posted by Li Nan 1 year, 7 months ago


在 2024/4/28 15:51, Zhihao Cheng 写道:
> 在 2024/4/28 15:19, linan666@huaweicloud.com 写道:
>> 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);
> 
> There is no need to modify this place. The device of 'gd' is initialized in 
> blk_mq_alloc_disk. Refer to nbd_dev_add.


The print of this dev_err() is:
   block (null): block: dynamic minor allocation failed
	~~~~~~
There is no information about which device failed. dev_err()
use 'kobject_name(&dev->kobj)' here, which is init in device_add_disk()
later. So use pr_err() here can print more detail.

I will split the patch into two in v2 to make it clearer.

>>       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;
>>       }
>>

-- 
Thanks,
Nan