linux-kernel - Re: [PATCH] staging: media: atomisp: add missing mutex lock in atomisp_s_fmt

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Message-ID: <CAHp75Ve6rE22crmt5mUioWtkWm_-ODV+Dk2gcTQ8ickhMMkvAQ@mail.gmail.com>
Date: Wed, 16 Jul 2025 11:10:59 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Abdelrahman Fekry <abdelrahmanfekry375@...il.com>
Cc: hansg@...nel.org, mchehab@...nel.org, sakari.ailus@...ux.intel.com, 
	andy@...nel.org, gregkh@...uxfoundation.org, linux-media@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-staging@...ts.linux.dev, 
	linux-kernel-mentees@...ts.linux.dev, skhan@...uxfoundation.org, 
	dan.carpenter@...aro.org
Subject: Re: [PATCH] staging: media: atomisp: add missing mutex lock in atomisp_s_fmt_cap

On Wed, Jul 16, 2025 at 4:42 AM Abdelrahman Fekry
<abdelrahmanfekry375@...il.com> wrote:
>
> The function atomisp_set_fmt() modifies shared device state and expects
> callers to hold the isp->mutex for synchronization. While most internal
> callers correctly lock the mutex before invoking atomisp_set_fmt(), the
> V4L2 ioctl handler atomisp_s_fmt_cap() does not.
>
> This results in an unsafe execution path for VIDIOC_S_FMT ioctls
> (e.g. via v4l2-ctl), where shared structures such as pipe->pix and
> pipe->frame_info may be modified concurrently without proper protection.
>
> - Fix this by explicitly locking isp->mutex in atomisp_s_fmt_cap().

If it's a fix, please add the Fixes tag.

...

> -       return atomisp_set_fmt(vdev, f);
> +       mutex_lock(&isp->mutex);
> +       ret = atomisp_set_fmt(vdev, f);
> +       mutex_unlock(&isp->mutex);

Side note: Can you consider switching the driver to use cleanup.h
(guard()(), scoped_guard(), __free(), etc)?

-- 
With Best Regards,
Andy Shevchenko