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Date:   Sat, 10 Sep 2022 18:14:45 -0100
From:   Melissa Wen <mwen@igalia.com>
To:     Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Cc:     Haneen Mohammed <hamohammed.sa@gmail.com>,
        Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>,
        David Airlie <airlied@linux.ie>, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org,
        Melissa Wen <melissa.srw@gmail.com>, dan.carpenter@oracle.com,
        Igor Torrente <igormtorrente@gmail.com>
Subject: Re: [PATCH] drm/vkms: fix variable dereferenced before check warning
Message-ID: <20220910191429.ifyzdp54due3u7it@mail.igalia.com>
References: <20220908105623.72777-1-harshit.m.mogalapalli@oracle.com>
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On 09/08, Harshit Mogalapalli wrote:
> Smatch warns:
>=20
> drivers/gpu/drm/vkms/vkms_plane.c:110 vkms_plane_atomic_update() warn:
>  variable dereferenced before check 'fb' (see line 108)
>=20
> Fix the warning by moving the dereference after the NULL check.
>=20
> Fixes: 8ba1648567e2 ("drm: vkms: Refactor the plane composer to accept ne=
w formats")
> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
> ---
>  drivers/gpu/drm/vkms/vkms_plane.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>=20
> diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkm=
s_plane.c
> index f4319066adcc..c3a845220e10 100644
> --- a/drivers/gpu/drm/vkms/vkms_plane.c
> +++ b/drivers/gpu/drm/vkms/vkms_plane.c
> @@ -105,11 +105,12 @@ static void vkms_plane_atomic_update(struct drm_pla=
ne *plane,
>  	struct drm_shadow_plane_state *shadow_plane_state;
>  	struct drm_framebuffer *fb =3D new_state->fb;
>  	struct vkms_frame_info *frame_info;
> -	u32 fmt =3D fb->format->format;
> +	u32 fmt;
> =20
>  	if (!new_state->crtc || !fb)
>  		return;
> =20
> +	fmt =3D fb->format->format;

Hi Harshit,

Nice catch.

Thanks,

Reviewed-by: Melissa Wen <mwen@igalia.com>

>  	vkms_plane_state =3D to_vkms_plane_state(new_state);
>  	shadow_plane_state =3D &vkms_plane_state->base;
> =20
> --=20
> 2.31.1
>=20

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