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

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Message-ID: <4385d754-acbb-30b8-f311-ba542a8211e9@huaweicloud.com>
Date:   Fri, 8 Dec 2023 15:40:40 +0800
From:   Li Nan <linan666@...weicloud.com>
To:     Zhihao Cheng <chengzhihao1@...wei.com>, linan666@...weicloud.com,
        richard@....at, miquel.raynal@...tlin.com, vigneshr@...com
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] ubi: block: fix null-pointer-dereference in
 ubiblock_create()



在 2023/12/8 15:29, Zhihao Cheng 写道:
> 在 2023/12/8 15:13, linan666@...weicloud.com 写道:
>> From: Li Nan <linan122@...wei.com>
>>
>> If idr_alloc() fails, dev->gd will be put after goto out_cleanup_disk in
>> ubiblock_create(), but dev->gd has not been assigned yet at this time, 
>> and
>> accessing it will trigger a null-pointer-dereference issue. Fix it by put
>> gd directly.
> Function 'put_disk()' checks disk whether is NULL, so I think it's a 
> 'memleak' problem, not a null-ptr-deref problem.
>>

Damn, I overlooked it here. Thanks for your review, I will fix the log
in v2.

>> Signed-off-by: Li Nan <linan122@...wei.com>
>> ---
>>   drivers/mtd/ubi/block.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
>> index 309a42aeaa4c..654bd7372cd8 100644
>> --- a/drivers/mtd/ubi/block.c
>> +++ b/drivers/mtd/ubi/block.c
>> @@ -434,7 +434,7 @@ int ubiblock_create(struct ubi_volume_info *vi)
>>       list_del(&dev->list);
>>       idr_remove(&ubiblock_minor_idr, gd->first_minor);
>>   out_cleanup_disk:
>> -    put_disk(dev->gd);
>> +    put_disk(gd);
> 
> For memleak solution:
> 
> Reviewed-by: Zhihao Cheng <chengzhihao1@...wei.com>
> 
>>   out_free_tags:
>>       blk_mq_free_tag_set(&dev->tag_set);
>>   out_free_dev:
> 
> 
> .

-- 
Thanks,
Nan