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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id s2sm22248102pfe.215.2021.10.26.10.14.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 26 Oct 2021 10:14:36 -0700 (PDT) Date: Tue, 26 Oct 2021 10:14:36 -0700 From: Kees Cook To: Ard Biesheuvel Cc: linux@armlinux.org.uk, linus.walleij@linaro.org, arnd@arndb.de, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] ARM: decompressor: disable stack protector Message-ID: <202110261013.7A0CE6D71@keescook> References: <20211026082752.3519140-1-ardb@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20211026082752.3519140-1-ardb@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211026_101438_419890_4FD9F410 X-CRM114-Status: GOOD ( 15.76 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Oct 26, 2021 at 10:27:52AM +0200, Ard Biesheuvel wrote: > Enabling the stack protector in the decompressor is of dubious value, > given that it uses a fixed value for the canary, cannot print any output > unless CONFIG_DEBUG_LL is enabled (which relies on board specific build > time settings), and is already disabled for a good chunk of the code > (libfdt). > > So let's just disable it in the decompressor. This will make it easier > in the future to manage the command line options that would need to be > removed again in this context for the TLS register based stack > protector. > > Signed-off-by: Ard Biesheuvel Yeah, that's fine. There's no good reason to complicate the decompressor for the stack protector. If someone is trying to exploit the kernel at this stage, the system has a much bigger problem. ;) Acked-by: Kees Cook -- Kees Cook _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel