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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id s23sm2178658pjq.17.2020.01.28.14.50.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jan 2020 14:50:02 -0800 (PST) Date: Tue, 28 Jan 2020 14:50:00 -0800 From: Kees Cook To: Sami Tolvanen Subject: Re: [PATCH v7 04/11] scs: disable when function graph tracing is enabled Message-ID: <202001281449.FB1671805E@keescook> References: <20191018161033.261971-1-samitolvanen@google.com> <20200128184934.77625-1-samitolvanen@google.com> <20200128184934.77625-5-samitolvanen@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200128184934.77625-5-samitolvanen@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200128_145003_746890_B12B5669 X-CRM114-Status: GOOD ( 18.95 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , clang-built-linux@googlegroups.com, Ard Biesheuvel , Masahiro Yamada , Catalin Marinas , Jann Horn , Nick Desaulniers , linux-kernel@vger.kernel.org, Steven Rostedt , Miguel Ojeda , james.morse@arm.com, Masami Hiramatsu , Marc Zyngier , kernel-hardening@lists.openwall.com, Laura Abbott , Will Deacon , Dave Martin , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jan 28, 2020 at 10:49:27AM -0800, Sami Tolvanen wrote: > The graph tracer hooks returns by modifying frame records on the > (regular) stack, but with SCS the return address is taken from the > shadow stack, and the value in the frame record has no effect. As we > don't currently have a mechanism to determine the corresponding slot > on the shadow stack (and to pass this through the ftrace > infrastructure), for now let's disable SCS when the graph tracer is > enabled. > > Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook -Kees > --- > arch/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/Kconfig b/arch/Kconfig > index 1b16aa9a3fe5..0d746373c52e 100644 > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -530,6 +530,7 @@ config ARCH_SUPPORTS_SHADOW_CALL_STACK > > config SHADOW_CALL_STACK > bool "Clang Shadow Call Stack" > + depends on !FUNCTION_GRAPH_TRACER > depends on ARCH_SUPPORTS_SHADOW_CALL_STACK > help > This option enables Clang's Shadow Call Stack, which uses a > -- > 2.25.0.341.g760bfbb309-goog > -- Kees Cook _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel