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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id d2sm10586968pfc.1.2020.06.22.14.04.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Jun 2020 14:04:05 -0700 (PDT) Date: Mon, 22 Jun 2020 14:04:04 -0700 From: Kees Cook To: Nick Desaulniers Cc: LKML , Linus Torvalds , Miguel Ojeda , Alexander Potapenko , Joe Perches , Andy Whitcroft , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , drbd-dev@lists.linbit.com, linux-block@vger.kernel.org, b43-dev@lists.infradead.org, Network Development , Linux Doc Mailing List , linux-wireless , linux-ide@vger.kernel.org, linux-clk@vger.kernel.org, linux-spi@vger.kernel.org, Linux Memory Management List , clang-built-linux Subject: Re: [PATCH v2 04/16] b43: Remove uninitialized_var() usage Message-ID: <202006221403.EEAD37E94B@keescook> References: <20200620033007.1444705-1-keescook@chromium.org> <20200620033007.1444705-5-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 725DE18086E22 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Jun 22, 2020 at 10:04:18AM -0700, Nick Desaulniers wrote: > On Fri, Jun 19, 2020 at 8:30 PM Kees Cook 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 > > 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