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Date: Thu, 4 Jun 2020 13:20:00 -0700
From: Kees Cook <keescook@chromium.org>
To: Nick Desaulniers <ndesaulniers@google.com>
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Cc: Andy Whitcroft <apw@canonical.com>,
	clang-built-linux <clang-built-linux@googlegroups.com>,
	linux-ide@vger.kernel.org, Network Development <netdev@vger.kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	"maintainer:X86 ARCHITECTURE \(32-BIT AND 64-BIT\)" <x86@kernel.org>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>, linux-spi@vger.kernel.org,
	linux-block@vger.kernel.org,
	Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
	Linux Memory Management List <linux-mm@kvack.org>,
	Alexander Potapenko <glider@google.com>,
	b43-dev@lists.infradead.org, Joe Perches <joe@perches.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-clk@vger.kernel.org, drbd-dev@lists.linbit.com
Subject: Re: [Drbd-dev] [PATCH 05/10] ide: Remove uninitialized_var() usage
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On Thu, Jun 04, 2020 at 12:29:17PM -0700, Nick Desaulniers wrote:
> On Wed, Jun 3, 2020 at 4:32 PM Kees Cook <keescook@chromium.org> wrote:
> >
> > Using uninitialized_var() is dangerous as it papers over real bugs[1]
> > (or can in the future), and suppresses unrelated compiler warnings (e.g.
> > "unused variable"). If the compiler thinks it is uninitialized, either
> > simply initialize the variable or make compiler changes. As a precursor
> > to removing[2] this[3] macro[4], just remove this variable since it was
> > actually unused:
> >
> > drivers/ide/ide-taskfile.c:232:34: warning: unused variable 'flags' [-Wunused-variable]
> >         unsigned long uninitialized_var(flags);
> >                                         ^
> >
> > [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
> > [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
> > [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
> > [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
> >
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> 
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

Thanks for the reviews!

> Fixes ce1e518190ea ("ide: don't disable interrupts during kmap_atomic()")

I originally avoided adding Fixes tags because I didn't want these
changes backported into a -stable without -Wmaybe-uninitialized
disabled, but in these cases (variable removal), that actually does make
sense. Thanks!

-Kees

-- 
Kees Cook