Re: [PATCH 1/1] drm: use drm_warn() in validate_blend_mode_for_alpha_formats()

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Unconditional dereference of `drm_format_info()` return value leads to NULL pointer dereference for unrecognized formats.
--

--- Patch [1]: [PATCH 1/1] drm: use drm_warn() in validate_blend_mode_for_alpha_formats() ---
commit 8bcc8b572cfd0496af9f1e8dd202524f50670fa0
Author: Leandro Ribeiro <leandro.ribeiro@collabora.com>

drm: use drm_warn() in validate_blend_mode_for_alpha_formats()

This commit replaces WARN() with drm_warn() in
validate_blend_mode_for_alpha_formats() to prevent fuzzers from tripping
over kernel warning reports for expected driver validation issues.

> diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
> index 3bcc7bf0900c4..3d9c554e08a87 100644
> --- a/drivers/gpu/drm/drm_mode_config.c
> +++ b/drivers/gpu/drm/drm_mode_config.c
> @@ -869,8 +869,9 @@ static void validate_blend_mode_for_alpha_formats(struct drm_plane *plane)
>  	for (i = 0; i < plane->format_count; i++) {
>  		fmt = drm_format_info(plane->format_types[i]);
>  		if (fmt->has_alpha) {

[Severity: High]
This is a pre-existing issue, but could this unconditionally dereference
fmt if drm_format_info() returns NULL?

If a driver exposes an unrecognized or custom pixel format that the core
DRM does not know about, drm_format_info() returns NULL. Since the
purpose of this validation function is to catch driver bugs, should we
check if fmt is NULL before checking fmt->has_alpha to avoid a kernel
panic?

> -			WARN(1, "[PLANE:%d:%s] pixel format with alpha exposed but blend mode not setup",
> -			     plane->base.id, plane->name);
> +			drm_warn(plane->dev,
> +				 "[PLANE:%d:%s] pixel format with alpha exposed but blend mode not setup",
> +				 plane->base.id, plane->name);
>  			break;
>  		}
>  	}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260729214505.185776-2-leandro.ribeiro@collabora.com?part=1