linux-hardening - Re: [PATCH v2] iio: pressure: dlhl60d: Initialize empty DLH bytes

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Message-ID: <202402230949.E06F3297@keescook>
Date: Fri, 23 Feb 2024 09:50:10 -0800
From: Kees Cook <keescook@...omium.org>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Jonathan Cameron <jic23@...nel.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
	Nuno Sá <nuno.sa@...log.com>,
	linux-iio@...r.kernel.org, Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>, llvm@...ts.linux.dev,
	Tomislav Denis <tomislav.denis@....com>,
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2] iio: pressure: dlhl60d: Initialize empty DLH bytes

On Fri, Feb 23, 2024 at 07:47:36PM +0200, Andy Shevchenko wrote:
> On Fri, Feb 23, 2024 at 09:29:39AM -0800, Kees Cook wrote:
> > 3 bytes were being read but 4 were being written. Explicitly initialize
> > the unused bytes to 0 and refactor the loop to use direct array
> > indexing, which appears to silence a Clang false positive warning[1].
> 
> ...
> 
> >  	for_each_set_bit(chn, indio_dev->active_scan_mask,
> > -		indio_dev->masklength) {
> > -		memcpy(tmp_buf + i,
> > +			 indio_dev->masklength) {
> > +		memcpy(&tmp_buf[i++],
> >  			&st->rx_buf[1] + chn * DLH_NUM_DATA_BYTES,
> >  			DLH_NUM_DATA_BYTES);
> > -		i++;
> >  	}
> 
> Not that I'm against the changes, but they (in accordance with the commit
> message) are irrelevant to this fix. I prefer fixes to be more focused on
> the real issues.

Jonathan, let me know if you'd prefer I split this patch...

-- 
Kees Cook