linux-kernel - Re: [PATCH v2] mtd: core: always verify OOB offset in mtd_check_oob

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Message-ID: <87y0ql80nc.fsf@bootlin.com>
Date: Thu, 11 Sep 2025 17:33:11 +0200
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: Pratyush Yadav <pratyush@...nel.org>
Cc: Gabor Juhos <j4g8y7@...il.com>,  Santhosh Kumar K <s-k6@...com>,
  Richard Weinberger <richard@....at>,  Vignesh Raghavendra
 <vigneshr@...com>,  linux-mtd@...ts.infradead.org,
  linux-kernel@...r.kernel.org,  stable@...r.kernel.org,  Daniel Golle
 <daniel@...rotopia.org>
Subject: Re: [PATCH v2] mtd: core: always verify OOB offset in
 mtd_check_oob_ops()

On 11/09/2025 at 16:05:31 +02, Miquel Raynal <miquel.raynal@...tlin.com> wrote:

>>> Sorry for the inconvenience.
>>>
>>>> Gabor, can you check what happens with mtdblock?
>>
>> My guess from a quick look at the code is that NOR devices have
>> mtd->oobsize == 0 and mtd_read() sets ops->ooboffs and ops->ooblen to 0.
>> So now that this check is not guarded by if (ops->ooblen), it gets
>> triggered for NOR devices on the mtd_read() path and essentially turns
>> into an if (0 >= 0), returning -EINVAL.
>>
>> Maybe a better check is if ((ops->ooboffs + ops->ooblen) >
>> mtd_oobavail())?
>
> Interesting, might make sense to do it this way.
>
> Thanks Pratyush for the suggestion, it is worth the try.

I actually have another patch series to remove and I don't have more
time to dedicate to these issues at the moment, so I will force push and
drop all the problematic patches. More testing is needed.

Thanks,
Miquèl