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

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Message-ID: <a208824c-acf6-4a48-8fde-f9926a6e4db5@gmail.com>
Date: Thu, 11 Sep 2025 10:33:48 +0200
From: Gabor Juhos <j4g8y7@...il.com>
To: Miquel Raynal <miquel.raynal@...tlin.com>, Santhosh Kumar K <s-k6@...com>
Cc: 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()

Hi Miquel, Santhosh,

2025. 09. 11. 10:00 keltezéssel, Miquel Raynal írta:
> Hello,
> 
> On 11/09/2025 at 11:52:27 +0530, Santhosh Kumar K <s-k6@...com> wrote:
> 
>> Hello,
>>
>> On 05/09/25 20:25, Miquel Raynal wrote:
>>> On Mon, 01 Sep 2025 16:24:35 +0200, Gabor Juhos wrote:
>>>> Using an OOB offset past end of the available OOB data is invalid,
>>>> irregardless of whether the 'ooblen' is set in the ops or not. Move
>>>> the relevant check out from the if statement to always verify that.
>>>>
>>>> The 'oobtest' module executes four tests to verify how reading/writing
>>>> OOB data past end of the devices is handled. It expects errors in case
>>>> of these tests, but this expectation fails in the last two tests on
>>>> MTD devices, which have no OOB bytes available.
>>>>
>>>> [...]
>>> Applied to mtd/next, thanks!
>>> [1/1] mtd: core: always verify OOB offset in mtd_check_oob_ops()
>>>        commit: bf7d0543b2602be5cb450d8ec5a8710787806f88
>>
>> I'm seeing a failure in SPI NOR flashes due to this patch:
>> (Tested on AM62x SK with S28HS512T OSPI NOR flash)

Sorry for the inconvenience.

> Gabor, can you check what happens with mtdblock?

The strange thing is that it works with (SPI) NAND flashes:

# cat /sys/class/mtd/mtd0/type
nand
# cat /sys/class/mtd/mtd0/oobavail
0
#
# hexdump -n 2048 /dev/mtd0
0000000 0f0f 0f0f 0f0f 0f0f 0f0f 0f0f 0f0f 0f0f
*
0000800
#

I will check why it fails with NOR devices.

> Otherwise this will need to be reverted.

Please drop the patch for now, or revert it if dropping not possible.

Either I will send a fixed version, or we will have to live without the change.


Regards,
Gabor