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Message-ID: <664bd195bdde7fd740572c4981c60b32de1465aa.camel@collabora.com>
Subject: Re: [PATCH] vcodec: mediatek: add check for NULL for 
 vsi->frm_bufs[vsi->new_fb_idx].buf.fb in vp9_swap_frm_bufs
From:   Nicolas Dufresne <nicolas.dufresne@collabora.com>
To:     Anastasia Belova <abelova@astralinux.ru>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>
Cc:     Tiffany Lin <tiffany.lin@mediatek.com>,
        Andrew-CT Chen <andrew-ct.chen@mediatek.com>,
        Yunfei Dong <yunfei.dong@mediatek.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, lvc-project@linuxtesting.org
Date:   Fri, 28 Oct 2022 09:02:35 -0400
In-Reply-To: <20221028125811.11340-1-abelova@astralinux.ru>
References: <20221028125811.11340-1-abelova@astralinux.ru>
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Hi,

Le vendredi 28 octobre 2022 =C3=A0 15:58 +0300, Anastasia Belova a =C3=A9cr=
it=C2=A0:
> If vsi->frm_bufs[vsi->new_fb_idx].buf.fb =3D=3D NULL while cleaning
> fb_free_list NULL-pointer is dereferenced.
>=20
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>=20
> Fixes: f77e89854b3e ("[media] vcodec: mediatek: Add Mediatek VP9 Video De=
coder Driver")
>=20
> Signed-off-by: Anastasia Belova <abelova@astralinux.ru>
> ---
>  drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c b/=
drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c
> index 70b8383f7c8e..b0679aaf6192 100644
> --- a/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c
> +++ b/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_if.c
> @@ -512,7 +512,7 @@ static void vp9_swap_frm_bufs(struct vdec_vp9_inst *i=
nst)
>  	 * clean fb_free_list
>  	 */
>  	if (vsi->frm_bufs[vsi->new_fb_idx].ref_cnt =3D=3D 0) {
> -		if (!vp9_is_sf_ref_fb(
> +		if (vsi->frm_bufs[vsi->new_fb_idx].buf.fb !=3D NULL && !vp9_is_sf_ref_=
fb(
>  			inst, vsi->frm_bufs[vsi->new_fb_idx].buf.fb)) {
>  			struct vdec_fb *fb;

Perhaps we could try and maintain some readability ? I'd suggest to move th=
e
check into vp9_is_sf_ref_fb() as an early return.

Nicolas