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

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Message-ID: <005438a1d81a1d02d6c8659bd951ff65d3f39d85.camel@collabora.com>
Date: Tue, 02 Sep 2025 08:57:54 -0400
From: Nicolas Dufresne <nicolas.dufresne@...labora.com>
To: Irui Wang (王瑞) <Irui.Wang@...iatek.com>,
  "rongqianfeng@...o.com"	 <rongqianfeng@...o.com>, "matthias.bgg@...il.com"
 <matthias.bgg@...il.com>,  "mchehab@...nel.org"	 <mchehab@...nel.org>,
 AngeloGioacchino Del Regno	 <angelogioacchino.delregno@...labora.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

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.

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/

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