linux-kernel - Re: [PATCH v2] media: mediatek: encoder: Fix uninitialized scalar variable issue

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Message-ID: <820d9e864019a25a9b552ac73fd4324642f1e415.camel@mediatek.com>
Date: Sun, 7 Sep 2025 09:44:15 +0000
From: Irui Wang (王瑞) <Irui.Wang@...iatek.com>
To: "matthias.bgg@...il.com" <matthias.bgg@...il.com>, "mchehab@...nel.org"
	<mchehab@...nel.org>, AngeloGioacchino Del Regno
	<angelogioacchino.delregno@...labora.com>, "nicolas.dufresne@...labora.com"
	<nicolas.dufresne@...labora.com>, "rongqianfeng@...o.com"
	<rongqianfeng@...o.com>, "hverkuil-cisco@...all.nl"
	<hverkuil-cisco@...all.nl>
CC: "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-media@...r.kernel.org"
	<linux-media@...r.kernel.org>, "linux-mediatek@...ts.infradead.org"
	<linux-mediatek@...ts.infradead.org>,
	Longfei Wang (王龙飞) <Longfei.Wang@...iatek.com>,
	Project_Global_Chrome_Upstream_Group
	<Project_Global_Chrome_Upstream_Group@...iatek.com>,
	Yunfei Dong (董云飞) <Yunfei.Dong@...iatek.com>
Subject: Re: [PATCH v2] media: mediatek: encoder: Fix uninitialized scalar
 variable issue

Dear Nicolas,


On Tue, 2025-09-02 at 08:57 -0400, Nicolas Dufresne wrote:
> Le lundi 01 septembre 2025 à 02:37 +0000, Irui Wang (王瑞) a écrit :
> > Dear Nicolas,
> > 
> > Thanks for your comments.
> > 
> > On Fri, 2025-08-29 at 15:10 -0400, Nicolas Dufresne wrote:
> > > Le mercredi 16 juillet 2025 à 15:14 +0800, Irui Wang a écrit :
> > > > UNINIT checker finds some instances of variables that are used
> > > > without being initialized, for example using the uninitialized
> > > > value enc_result.is_key_frm can result in unpredictable
> > > > behavior,
> > > > so initialize these variables after declaring.
> > > > 
> > > > Fixes: 4e855a6efa54 ("[media] vcodec: mediatek: Add Mediatek
> > > > V4L2
> > > > Video
> > > > Encoder Driver")
> > > > 
> > > > Signed-off-by: Irui Wang <irui.wang@...iatek.com>
> > > > ---
> > > > v2:
> > > >  - Add Fixes tag, update commit message
> > > >  - Remove unnecessary memset
> > > >  - Move memset to before the first usage
> > > > ---
> > > >  .../media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc.c  
> > > > | 4
> > > > +++-
> > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git
> > > > a/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc
> > > > .c
> > > > b/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc
> > > > .c
> > > > index a01dc25a7699..3065f3e66336 100644
> > > > ---
> > > > a/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc
> > > > .c
> > > > +++
> > > > b/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc
> > > > .c
> > > > @@ -865,7 +865,7 @@ static void vb2ops_venc_buf_queue(struct
> > > > vb2_buffer *vb)
> > > >  static int vb2ops_venc_start_streaming(struct vb2_queue *q,
> > > > unsigned int
> > > > count)
> > > >  {
> > > >  	struct mtk_vcodec_enc_ctx *ctx = vb2_get_drv_priv(q);
> > > > -	struct venc_enc_param param;
> > > > +	struct venc_enc_param param = { 0 };
> > > >  	int ret;
> > > >  	int i;
> > > >  
> > > > @@ -1036,6 +1036,7 @@ static int mtk_venc_encode_header(void
> > > > *priv)
> > > >  			  ctx->id, dst_buf->vb2_buf.index,
> > > > bs_buf.va,
> > > >  			  (u64)bs_buf.dma_addr, bs_buf.size);
> > > >  
> > > > +	memset(&enc_result, 0, sizeof(enc_result));
> > > 
> > > Please, apply review comment to all occurrence, so same here.
> > > 
> > > >  	ret = venc_if_encode(ctx,
> > > >  			VENC_START_OPT_ENCODE_SEQUENCE_HEADER,
> > > >  			NULL, &bs_buf, &enc_result);
> > > > @@ -1185,6 +1186,7 @@ static void mtk_venc_worker(struct
> > > > work_struct *work)
> > > >  			  (u64)frm_buf.fb_addr[1].dma_addr,
> > > > frm_buf.fb_addr[1].size,
> > > >  			  (u64)frm_buf.fb_addr[2].dma_addr,
> > > > frm_buf.fb_addr[2].size);
> > > >  
> > > > +	memset(&enc_result, 0, sizeof(enc_result));
> > > 
> > > Same here.
> > > 
> > > >  	ret = venc_if_encode(ctx, VENC_START_OPT_ENCODE_FRAME,
> > > >  			     &frm_buf, &bs_buf, &enc_result);
> > > >  
> > > > 
> > > 
> > > 
> > > Would be nice to coordinate with Qianfeng Rong <
> > > rongqianfeng@...o.com
> > > > [0], he
> > > 
> > > ported the entire driver to this initialization method, which is
> > > clearly the way
> > > to go.
> > > 
> > > - Patch 1 will port the driver to {} stack init
> > > - Patch 2 will add missing initializes
> > > 
> > > Consistency is key for this type of things since developer
> > > usually
> > > follow the
> > > surrounding style.
> > 
> > I have learned Qianfeng's patch and comments. I understand what you
> > mean is change my patch coding style to Qianfeng's, modify 'memset'
> > to
> > '{}' for initialization, and amend Qianfeng's patch as patch-2,
> > then
> > send this two patches together.
> 
> Correct, and I don't mind who do that work, I'd like to see the code
> kept
> consistant. And I do agree memset() are error prone.

patch v3 has sent, please kindly help to review when you have time,
thank you very much.

https://patchwork.linuxtv.org/project/linux-media/list/?series=18118

> 
> cheers,
> Nicolas
> 
> > 
> > If I misunderstood your opinion, please correct me, thank you very
> > much.
> > 
> > Best Regards
> > > 
> > > regards
> > > Nicolas
> > > 
> > > [0] 
> > > 
https://patchwork.linuxtv.org/project/linux-media/patch/20250803135514.118892-1-rongqianfeng@vivo.com/