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Date:   Sun, 30 Jul 2023 11:46:24 +0200
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Subject: Re: [PATCH] md: fix potential OOB in multipath_remove_disk()
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To:     Song Liu <song@kernel.org>,
        Zhang Shurong <zhang_shurong@foxmail.com>,
        Christoph Hellwig <hch@infradead.org>
Cc:     linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org
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From:   Paul Menzel <pmenzel@molgen.mpg.de>
In-Reply-To: <CAPhsuW54pW7As-A1G4H+OWALUh7_a5+-zkLXghTh6_JjcWZoMQ@mail.gmail.com>
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Dear Song, Zhang and Christoph,


Am 29.07.23 um 12:46 schrieb Song Liu:
> On Sat, Jul 15, 2023 at 5:45 PM Zhang Shurong wrote:
>>
>> 在 2023年7月13日星期四 CST 上午12:50:19，Christoph Hellwig 写道：
>>> On Thu, Jul 13, 2023 at 12:46:05AM +0800, Zhang Shurong wrote:
>>>> If rddev->raid_disk is greater than mddev->raid_disks, there will be
>>>> an out-of-bounds in multipath_remove_disk. We have already found
>>>> similar reports as follows:
>>>>
>>>> 1) commit d17f744e883b ("md-raid10: fix KASAN warning")
>>>> 2) commit 1ebc2cec0b7d ("dm raid: fix KASAN warning in raid5_remove_disk")
>>>>
>>>> Fix this bug by checking whether the "number" variable is
>>>> valid.
>>>
>>> I think it might just be time to finally dropped the deprecated md
>>> multipath code instead..
>> Should I write another patch to delete them?
> 
> Yes, please write a patch to delete the multipath code.

How would fixing this bug work with the stable series? Probably a 
removal patch wouldn’t be picked, right? Shouldn’t the fix be accepted 
in master, and then the code be removed?


Kind regards,

Paul