Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:2 as permitted sender) client-ip=2620:137:e000::3:2;
Subject: Re: [PATCH] ubi: block: fix null-pointer-dereference in
 ubiblock_create()
To:     <linan666@huaweicloud.com>, <richard@nod.at>,
        <miquel.raynal@bootlin.com>, <vigneshr@ti.com>
CC:     <linux-mtd@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
        <linan122@huawei.com>, <yukuai3@huawei.com>, <yi.zhang@huawei.com>,
        <houtao1@huawei.com>, <yangerkun@huawei.com>
References: <20231208071317.1268465-1-linan666@huaweicloud.com>
From:   Zhihao Cheng <chengzhihao1@huawei.com>
Message-ID: <a1e3aa71-d89e-0579-b55f-125c17b45f29@huawei.com>
Date:   Fri, 8 Dec 2023 15:29:35 +0800
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101
 Thunderbird/68.5.0
MIME-Version: 1.0
In-Reply-To: <20231208071317.1268465-1-linan666@huaweicloud.com>
Content-Type: text/plain; charset="gbk"; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk

?? 2023/12/8 15:13, linan666@huaweicloud.com д??:
> From: Li Nan <linan122@huawei.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.
>
> Signed-off-by: Li Nan <linan122@huawei.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@huawei.com>

>   out_free_tags:
>   	blk_mq_free_tag_set(&dev->tag_set);
>   out_free_dev: