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From: Kees Cook <keescook@chromium.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
	Alexander Potapenko <glider@google.com>,
	Joe Perches <joe@perches.com>, Andy Whitcroft <apw@canonical.com>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>,
	drbd-dev@lists.linbit.com, linux-block@vger.kernel.org,
	b43-dev@lists.infradead.org,
	Network Development <netdev@vger.kernel.org>,
	Linux Doc Mailing List <linux-doc@vger.kernel.org>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	linux-ide@vger.kernel.org, linux-clk@vger.kernel.org,
	linux-spi@vger.kernel.org,
	Linux Memory Management List <linux-mm@kvack.org>,
	clang-built-linux <clang-built-linux@googlegroups.com>
Subject: Re: [PATCH v2 04/16] b43: Remove uninitialized_var() usage
Date: Mon, 22 Jun 2020 14:04:04 -0700
Message-ID: <202006221403.EEAD37E94B@keescook> (raw)
In-Reply-To: <CAKwvOdmsXuqx-3Rt_KNFq4psAeFjG2-7qQaqkJ7dDqqmscUFNw@mail.gmail.com>

On Mon, Jun 22, 2020 at 10:04:18AM -0700, Nick Desaulniers wrote:
> On Fri, Jun 19, 2020 at 8:30 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 initialize this variable to NULL.
> > No later NULL deref is possible due to the early returns outside of the
> > (phy->rev >= 7 && phy->rev < 19) case, which explicitly tests for NULL.
> >
> > [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/
> >
> > Fixes: 58619b14d106 ("b43: move under broadcom vendor directory")
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> 
> I see three total uses of uninitialized_var() in this file, do we want
> to eliminate all of them?

This is the only one that needed an explicit initialization -- all the
others are handled in the treewide patch. I *could* split it out here,
but I found it easier to keep the "no op" changes together in the
treewide patch.

-Kees

> 
> > ---
> >  drivers/net/wireless/broadcom/b43/phy_n.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/wireless/broadcom/b43/phy_n.c b/drivers/net/wireless/broadcom/b43/phy_n.c
> > index c33b4235839d..46db91846007 100644
> > --- a/drivers/net/wireless/broadcom/b43/phy_n.c
> > +++ b/drivers/net/wireless/broadcom/b43/phy_n.c
> > @@ -4222,7 +4222,7 @@ static void b43_nphy_tx_gain_table_upload(struct b43_wldev *dev)
> >         u32 rfpwr_offset;
> >         u8 pga_gain, pad_gain;
> >         int i;
> > -       const s16 *uninitialized_var(rf_pwr_offset_table);
> > +       const s16 *rf_pwr_offset_table = NULL;
> >
> >         table = b43_nphy_get_tx_gain_table(dev);
> >         if (!table)
> > --
> 
> -- 
> Thanks,
> ~Nick Desaulniers

-- 
Kees Cook

  reply index

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-20  3:29 [PATCH v2 00/16] Remove uninitialized_var() macro Kees Cook
2020-06-20  3:29 ` [PATCH v2 01/16] docs: deprecated.rst: Add uninitialized_var() Kees Cook
2020-06-22 16:59   ` Nick Desaulniers
2020-06-20  3:29 ` [PATCH v2 02/16] x86/mm/numa: Remove uninitialized_var() usage Kees Cook
2020-06-20  3:29 ` [PATCH v2 03/16] drbd: " Kees Cook
2020-06-20  3:29 ` [PATCH v2 04/16] b43: " Kees Cook
2020-06-22 17:04   ` Nick Desaulniers
2020-06-22 21:04     ` Kees Cook [this message]
2020-06-23 18:29       ` Nick Desaulniers
2020-06-20  3:29 ` [PATCH v2 05/16] rtlwifi: rtl8192cu: " Kees Cook
2020-06-20  3:29 ` [PATCH v2 06/16] ide: " Kees Cook
2020-06-20  3:29 ` [PATCH v2 07/16] clk: st: " Kees Cook
2020-06-22  9:03   ` Stephen Boyd
2020-06-20  3:29 ` [PATCH v2 08/16] spi: davinci: " Kees Cook
2020-07-01 20:39   ` Mark Brown
2020-07-02 15:21     ` Kees Cook
2020-07-02 15:23       ` Mark Brown
2020-07-02 15:42         ` Kees Cook
2020-07-02 16:23           ` Joe Perches
2020-06-20  3:30 ` [PATCH v2 09/16] clk: spear: " Kees Cook
2020-06-22  9:03   ` Stephen Boyd
2020-06-20  3:30 ` [PATCH v2 10/16] KVM: PPC: Book3S PR: " Kees Cook
2020-06-22 17:22   ` Nick Desaulniers
2020-06-20  3:30 ` [PATCH v2 11/16] media: sur40: " Kees Cook
2020-06-22 18:39   ` Nick Desaulniers
2020-06-20  3:30 ` [PATCH v2 12/16] f2fs: Eliminate usage of uninitialized_var() macro Kees Cook
2020-06-20  3:30 ` [PATCH v2 14/16] checkpatch: Remove awareness " Kees Cook
2020-06-20  3:30 ` [PATCH v2 15/16] treewide: Remove uninitialized_var() usage Kees Cook
2020-06-20  3:30 ` [PATCH v2 16/16] compiler: Remove uninitialized_var() macro Kees Cook
2020-06-20  3:30 ` [PATCH v2 13/16] mm/debug_vm_pgtable: Remove uninitialized_var() usage Kees Cook
2020-06-22 17:27   ` Nick Desaulniers
2020-06-20  7:03 ` [PATCH v2 00/16] Remove uninitialized_var() macro Sedat Dilek
2020-06-20 15:57   ` Kees Cook
2020-06-22  9:07     ` Sedat Dilek

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