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s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=JXkDSAr5/uPdypFT+vPhb9QM0XECCw1QogkIjza9trI=; b=R0CUZRwMo1Kqu53mCDiMayj/eejOvaUhIsOc0bxRCskJVz0BOthV+p7+TiIeUdzHrD z+ZSsogfb7SJDmWWMevHreiPuw7IWsdylWFMAw7264TYZNaaZuyYfUxRKAAfOAygOh4W IoinGp970eVYb1MCzM4trzWkErS89T8XKlXO89GFq+s49Kjey0GG6Kk8LE7o8XgqMkpw Tzn9kvAUXu93lDpesZJuxMUgYNzCS2XJCRa/Z3PGTWEHIA24LCXTfNY/nwUghOwM5fSH LrXEGHW3PdNoozY699DzwzRz+VThavmtvXh72l1VC1KPipIpbwBIIEixaN/oJFmG9eok fdoA== X-Gm-Message-State: AOAM5308eG+v5mi1Myqr4tJes0ofsBWZGF7m65i3OoXRAkc/8IRJrCVf aRDX6VAx5G8vn7vajXFvIiJEv4nCGYozWnoEljDi6Q== X-Google-Smtp-Source: ABdhPJwFYRuJg9EUbjSytVc+yfQjuDOMjwE4SVCIBy3rni20OvAXlm0XdI+2Z8txK6JARtyDXhDgAzhgcWbhIpdXKAY= X-Received: by 2002:a17:902:fe8b:: with SMTP id x11mr24842368plm.179.1592936988375; Tue, 23 Jun 2020 11:29:48 -0700 (PDT) MIME-Version: 1.0 References: <20200620033007.1444705-1-keescook@chromium.org> <20200620033007.1444705-5-keescook@chromium.org> <202006221403.EEAD37E94B@keescook> In-Reply-To: <202006221403.EEAD37E94B@keescook> From: Nick Desaulniers Date: Tue, 23 Jun 2020 11:29:38 -0700 Message-ID: Subject: Re: [PATCH v2 04/16] b43: Remove uninitialized_var() usage To: Kees Cook 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 Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 1293A28A4EC X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 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 2:04 PM Kees Cook wrote: > > 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. Ah, got it. Reviewed-by: Nick Desaulniers > > -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 -- Thanks, ~Nick Desaulniers