linux-kernel - Re: [PATCH v3 3/3] drm/atomic: verify that gamma/degamma LUTs are not too big

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Message-ID: <f44ca674-775c-4e48-ab7c-9adb7881ff70@suse.de>
Date: Tue, 6 Jan 2026 08:25:46 +0100
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>, Harry Wentland <harry.wentland@....com>,
 Leo Li <sunpeng.li@....com>, Rodrigo Siqueira <siqueira@...lia.com>,
 Alex Deucher <alexander.deucher@....com>,
 Christian König <christian.koenig@....com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 amd-gfx@...ts.freedesktop.org
Subject: Re: [PATCH v3 3/3] drm/atomic: verify that gamma/degamma LUTs are not
 too big



Am 06.01.26 um 04:09 schrieb Dmitry Baryshkov:
> The kernel specifies LUT table sizes in a separate property, however it
> doesn't enforce it as a maximum. Some drivers implement max suze check

s/suze/size

> on their own in the atomic_check path. Other drivers simply ignore the
> issue. Perform LUT size validation in the generic place.
>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>

Reviewed-by: Thomas Zimmermann <tzimmermann@...e.de>

> ---
>   drivers/gpu/drm/drm_atomic_uapi.c | 22 ++++++++++++++++++++--
>   1 file changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
> index dff1fdefcbeb..dc013a22bf26 100644
> --- a/drivers/gpu/drm/drm_atomic_uapi.c
> +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> @@ -413,10 +413,19 @@ static int drm_atomic_crtc_set_property(struct drm_crtc *crtc,
>   	} else if (property == config->prop_vrr_enabled) {
>   		state->vrr_enabled = val;
>   	} else if (property == config->degamma_lut_property) {
> +		const size_t elem_size = sizeof(struct drm_color_lut);
> +		u64 lut_size;
> +
> +		ret = drm_object_immutable_property_get_value(&crtc->base,
> +							      config->degamma_lut_size_property,
> +							      &lut_size);
> +		if (ret)
> +			return ret;
> +
>   		ret = drm_property_replace_blob_from_id(dev,
>   					&state->degamma_lut,
>   					val,
> -					-1, -1, sizeof(struct drm_color_lut),
> +					elem_size * lut_size, -1, elem_size,
>   					&replaced);
>   		state->color_mgmt_changed |= replaced;
>   		return ret;
> @@ -429,10 +438,19 @@ static int drm_atomic_crtc_set_property(struct drm_crtc *crtc,
>   		state->color_mgmt_changed |= replaced;
>   		return ret;
>   	} else if (property == config->gamma_lut_property) {
> +		const size_t elem_size = sizeof(struct drm_color_lut);
> +		u64 lut_size;
> +
> +		ret = drm_object_immutable_property_get_value(&crtc->base,
> +							      config->gamma_lut_size_property,
> +							      &lut_size);
> +		if (ret)
> +			return ret;
> +
>   		ret = drm_property_replace_blob_from_id(dev,
>   					&state->gamma_lut,
>   					val,
> -					-1, -1, sizeof(struct drm_color_lut),
> +					elem_size * lut_size, -1, elem_size,
>   					&replaced);
>   		state->color_mgmt_changed |= replaced;
>   		return ret;
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)