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Date:   Thu, 26 Oct 2023 16:52:47 +0800
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Subject: Re: [PATCH] block: Fix minor range check in device_add_disk()
To:     Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, axboe@kernel.dk
Cc:     linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        zhongjinghua@huawei.com, yi.zhang@huawei.com, yukuai3@huawei.com
References: <20231025084621.2338604-1-zhongjinghua@huaweicloud.com>
 <119b7314-10a9-4d62-b40f-19462dc68009@I-love.SAKURA.ne.jp>
From:   zhongjinghua <zhongjinghua@huaweicloud.com>
In-Reply-To: <119b7314-10a9-4d62-b40f-19462dc68009@I-love.SAKURA.ne.jp>
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在 2023/10/25 18:06, Tetsuo Handa 写道:
> On 2023/10/25 17:46, Zhong Jinghua wrote:
>> Checks added in patch:
>> commit e338924bd05d ("block: check minor range in device_add_disk()")
>> ignore the problem of first_minore < 0 and disk->minors < 0.
> What is the problem of first_minor < 0 or disk->minors < 0 ?
> Are negative values legal/illegal ?

These two values are used as the secondary device number and the maximum number of partitions, which is illegal if negative. Then first_minore and disk->minors are signed numbers, and the sum may be less than MINORMASK to bypass the check.