linux-kernel - Re: [PATCH] drm/vkms: Adjust vkms_state->active

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Message-ID: <823d4d24-da80-4834-95ca-d5698edfe18f@bootlin.com>
Date: Mon, 28 Apr 2025 10:18:34 +0200
From: Louis Chauvet <louis.chauvet@...tlin.com>
To: Kees Cook <kees@...nel.org>
Cc: Haneen Mohammed <hamohammed.sa@...il.com>, Simona Vetter
 <simona@...ll.ch>, Melissa Wen <melissa.srw@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] drm/vkms: Adjust vkms_state->active_planes allocation
 type



Le 26/04/2025 à 08:14, Kees Cook a écrit :
> In preparation for making the kmalloc family of allocators type aware,
> we need to make sure that the returned type from the allocation matches
> the type of the variable being assigned. (Before, the allocator would
> always return "void *", which can be implicitly cast to any pointer type.)
> 
> The assigned type is "struct vkms_plane_state **", but the returned type
> will be "struct drm_plane **". These are the same size (pointer size), but
> the types don't match. Adjust the allocation type to match the assignment.

I think this is an issue, can you add the proper Fixup tag in this commit?

With this:

Reviewed-by: Louis Chauvet <louis.chauvet@...tlin.com>

> Signed-off-by: Kees Cook <kees@...nel.org>
> ---
> Cc: Louis Chauvet <louis.chauvet@...tlin.com>
> Cc: Haneen Mohammed <hamohammed.sa@...il.com>
> Cc: Simona Vetter <simona@...ll.ch>
> Cc: Melissa Wen <melissa.srw@...il.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
> Cc: Maxime Ripard <mripard@...nel.org>
> Cc: Thomas Zimmermann <tzimmermann@...e.de>
> Cc: David Airlie <airlied@...il.com>
> Cc: <dri-devel@...ts.freedesktop.org>
> ---
>   drivers/gpu/drm/vkms/vkms_crtc.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
> index 12034ec12029..8c9898b9055d 100644
> --- a/drivers/gpu/drm/vkms/vkms_crtc.c
> +++ b/drivers/gpu/drm/vkms/vkms_crtc.c
> @@ -194,7 +194,7 @@ static int vkms_crtc_atomic_check(struct drm_crtc *crtc,
>   		i++;
>   	}
>   
> -	vkms_state->active_planes = kcalloc(i, sizeof(plane), GFP_KERNEL);
> +	vkms_state->active_planes = kcalloc(i, sizeof(*vkms_state->active_planes), GFP_KERNEL);
>   	if (!vkms_state->active_planes)
>   		return -ENOMEM;
>   	vkms_state->num_active_planes = i;

-- 
Louis Chauvet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com