linux-kernel - Re: [BUG] Drivers/8255: Page fault in comedi

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Message-ID: <3e45e797-6c58-4937-a8b8-e71b869bbc97@mev.co.uk>
Date: Wed, 10 Dec 2025 10:06:50 +0000
From: Ian Abbott <abbotti@....co.uk>
To: Tianyu Li <2200013188@....pku.edu.cn>
Cc: linux-kernel <linux-kernel@...r.kernel.org>,
 hsweeten <hsweeten@...ionengravers.com>,
 xujiakai2025 <xujiakai2025@...as.ac.cn>,
 "zhaoruilin22@...ls.ucas.ac.cn" <zhaoruilin22@...ls.ucas.ac.cn>
Subject: Re: [BUG] Drivers/8255: Page fault in comedi_8255.c

On 09/12/2025 13:24, Tianyu Li wrote:
> Hi Ian,
> 
> Thank you for the detailed explanation — that clarifies the situation very well.
> 
> You mentioned that in linux-next the 8255 driver now returns an error immediately when reserving an I/O port region fails, which would also avoid the crash during fuzzing. I would like to take a closer look at that change.
> 
> &gt;   One thing that will affect the fuzzing tests is that the "8255" driver
> &gt;   in "linux-next" now returns an error as soon as it fails to reserve any
> &gt;   I/O port region, so unless the special base addresses (0x100 etc.)
> &gt;   appear early in the list before the conflicting base addresses, it won't
> &gt;   crash.
> 
> Could you please point me to the specific commit or patch where this improvement was introduced (a commit hash or link would be perfect if convenient)? This would help me better understand the context and verify the behavior on my side.

It's this one:

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=98d86d87aafb01e7c60b46d327a0a32619a167ff

> Thanks again for your guidance — I really appreciate your help.
> 
> Best regards,
> Tianyu Li

Kind regards,
Ian

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