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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id n185sm862325pfn.171.2021.08.18.15.30.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Aug 2021 15:30:02 -0700 (PDT) Date: Wed, 18 Aug 2021 15:30:01 -0700 From: Kees Cook To: Christophe Leroy Cc: linux-kernel@vger.kernel.org, Rasmus Villemoes , Greg Kroah-Hartman , Wang Wensheng , linux-staging@lists.linux.dev, linux-wireless@vger.kernel.org, "Gustavo A. R. Silva" , Qinglang Miao , linux-block@vger.kernel.org, Hulk Robot , clang-built-linux@googlegroups.com, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org, linux-kbuild@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH v2 61/63] powerpc: Split memset() to avoid multi-field overflow Message-ID: <202108181528.9CDB56FEC@keescook> References: <20210818060533.3569517-1-keescook@chromium.org> <20210818060533.3569517-62-keescook@chromium.org> <7630b0bc-4389-6283-d8b9-c532df916d60@csgroup.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7630b0bc-4389-6283-d8b9-c532df916d60@csgroup.eu> Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On Wed, Aug 18, 2021 at 08:42:18AM +0200, Christophe Leroy wrote: > > > Le 18/08/2021 à 08:05, Kees Cook a écrit : > > In preparation for FORTIFY_SOURCE performing compile-time and run-time > > field bounds checking for memset(), avoid intentionally writing across > > neighboring fields. > > > > Instead of writing across a field boundary with memset(), move the call > > to just the array, and an explicit zeroing of the prior field. > > > > Cc: Benjamin Herrenschmidt > > Cc: Qinglang Miao > > Cc: "Gustavo A. R. Silva" > > Cc: Hulk Robot > > Cc: Wang Wensheng > > Cc: linuxppc-dev@lists.ozlabs.org > > Signed-off-by: Kees Cook > > Reviewed-by: Michael Ellerman > > Link: https://lore.kernel.org/lkml/87czqsnmw9.fsf@mpe.ellerman.id.au > > --- > > drivers/macintosh/smu.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/macintosh/smu.c b/drivers/macintosh/smu.c > > index 94fb63a7b357..59ce431da7ef 100644 > > --- a/drivers/macintosh/smu.c > > +++ b/drivers/macintosh/smu.c > > @@ -848,7 +848,8 @@ int smu_queue_i2c(struct smu_i2c_cmd *cmd) > > cmd->read = cmd->info.devaddr & 0x01; > > switch(cmd->info.type) { > > case SMU_I2C_TRANSFER_SIMPLE: > > - memset(&cmd->info.sublen, 0, 4); > > + cmd->info.sublen = 0; > > + memset(&cmd->info.subaddr, 0, 3); > > subaddr[] is a table, should the & be avoided ? It results in the same thing, but it's better form to not have the &; I will fix this. > And while at it, why not use sizeof(subaddr) instead of 3 ? Agreed. :) Thanks! -- Kees Cook