Re: [PATCH v3 3/4] staging: media: Add support for the Allwinner A31 ISP

From: Dan Carpenter <dan.carpenter@oracle.com>
To: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Cc: linux-media@vger.kernel.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org,
	linux-staging@lists.linux.dev,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Chen-Yu Tsai <wens@csie.org>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	Samuel Holland <samuel@sholland.org>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Hans Verkuil <hans.verkuil@cisco.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Subject: Re: [PATCH v3 3/4] staging: media: Add support for the Allwinner A31 ISP
Date: Wed, 20 Apr 2022 11:53:39 +0300	[thread overview]
Message-ID: <20220420085339.GA2969@kadam> (raw)
In-Reply-To: <20220420085132.GC2951@kadam>

On Wed, Apr 20, 2022 at 11:51:33AM +0300, Dan Carpenter wrote:
> On Wed, Apr 20, 2022 at 09:50:42AM +0200, Paul Kocialkowski wrote:
> > Hi Dan,
> > 
> > On Wed 20 Apr 22, 10:42, Dan Carpenter wrote:
> > > I ran Smatch on this patch.
> > 
> > Thanks for doing this!
> > 
> > > On Fri, Apr 15, 2022 at 05:37:07PM +0200, Paul Kocialkowski wrote:
> > > > +void sun6i_isp_capture_configure(struct sun6i_isp_device *isp_dev)
> > > > +{
> > > > +	unsigned int width, height;
> > > > +	unsigned int stride_luma, stride_chroma = 0;
> > > > +	unsigned int stride_luma_div4, stride_chroma_div4;
> > > > +	const struct sun6i_isp_capture_format *format;
> > > > +	const struct v4l2_format_info *info;
> > > > +	u32 pixelformat;
> > > > +
> > > > +	sun6i_isp_capture_dimensions(isp_dev, &width, &height);
> > > > +	sun6i_isp_capture_format(isp_dev, &pixelformat);
> > > > +
> > > > +	format = sun6i_isp_capture_format_find(pixelformat);
> > > > +	if (WARN_ON(!format))
> > > > +		return;
> > > > +
> > > > +	sun6i_isp_load_write(isp_dev, SUN6I_ISP_MCH_SIZE_CFG_REG,
> > > > +			     SUN6I_ISP_MCH_SIZE_CFG_WIDTH(width) |
> > > > +			     SUN6I_ISP_MCH_SIZE_CFG_HEIGHT(height));
> > > > +
> > > > +	info = v4l2_format_info(pixelformat);
> > > > +	if (WARN_ON(!info))
> > > > +		return;
> > > > +
> > > > +	stride_luma = width * info->bpp[0];
> > > > +	stride_luma_div4 = DIV_ROUND_UP(stride_luma, 4);
> > > > +
> > > > +	if (info->comp_planes > 1) {
> > > > +		stride_chroma = width * info->bpp[1] / info->hdiv;
> > > > +		stride_chroma_div4 = DIV_ROUND_UP(stride_chroma, 4);
> > > 
> > > stride_chroma_div4 is not intialized on the else path.
> > 
> > One could say it's not an issue to put an uninitialized value in this situation
> > since the hardware won't be taking it into account but I'll initialize the value
> > early in the next iteration.
> > 
> 
> My understanding is that it will trigger a KASAN warning at run time.

Or is it KMEMsan?  One of those.  The one that complains about
uninitialized memory.

regards,
dan carpenter