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Message-ID: <c2bf9c25b5ba7d00cc476ed1389ad5e2dd9b2491.camel@redhat.com>
Subject: Re: [PATCH] drm/nouveau/dp: check for NULL nv_connector->native_mode
From:   Lyude Paul <lyude@redhat.com>
To:     Natalia Petrova <n.petrova@fintech.ru>,
        Ben Skeggs <bskeggs@redhat.com>
Cc:     Karol Herbst <kherbst@redhat.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, lvc-project@linuxtesting.org
Date:   Tue, 13 Jun 2023 16:40:17 -0400
In-Reply-To: <20230512111526.82408-1-n.petrova@fintech.ru>
References: <20230512111526.82408-1-n.petrova@fintech.ru>
Organization: Red Hat Inc.
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Reviewed-by: Lyude Paul <lyude@redhat.com>

Will push upstream in a bit

On Fri, 2023-05-12 at 14:15 +0300, Natalia Petrova wrote:
> Add checking for NULL before calling nouveau_connector_detect_depth() in
> nouveau_connector_get_modes() function because nv_connector->native_mode
> could be dereferenced there since connector pointer passed to
> nouveau_connector_detect_depth() and the same value of
> nv_connector->native_mode is used there.
>=20
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>=20
> Fixes: d4c2c99bdc83 ("drm/nouveau/dp: remove broken display depth functio=
n, use the improved one")
>=20
> Signed-off-by: Natalia Petrova <n.petrova@fintech.ru>
> ---
>  drivers/gpu/drm/nouveau/nouveau_connector.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>=20
> diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/dr=
m/nouveau/nouveau_connector.c
> index 086b66b60d91..5dbf025e6873 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_connector.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
> @@ -966,7 +966,7 @@ nouveau_connector_get_modes(struct drm_connector *con=
nector)
>  	/* Determine display colour depth for everything except LVDS now,
>  	 * DP requires this before mode_valid() is called.
>  	 */
> -	if (connector->connector_type !=3D DRM_MODE_CONNECTOR_LVDS)
> +	if (connector->connector_type !=3D DRM_MODE_CONNECTOR_LVDS && nv_connec=
tor->native_mode)
>  		nouveau_connector_detect_depth(connector);
> =20
>  	/* Find the native mode if this is a digital panel, if we didn't
> @@ -987,7 +987,7 @@ nouveau_connector_get_modes(struct drm_connector *con=
nector)
>  	 * "native" mode as some VBIOS tables require us to use the
>  	 * pixel clock as part of the lookup...
>  	 */
> -	if (connector->connector_type =3D=3D DRM_MODE_CONNECTOR_LVDS)
> +	if (connector->connector_type =3D=3D DRM_MODE_CONNECTOR_LVDS && nv_conn=
ector->native_mode)
>  		nouveau_connector_detect_depth(connector);
> =20
>  	if (nv_encoder->dcb->type =3D=3D DCB_OUTPUT_TV)

--=20
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat