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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id p4-20020a17090b010400b00267f1455d60sm1328pjz.20.2023.08.08.14.27.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Aug 2023 14:27:15 -0700 (PDT) Date: Tue, 8 Aug 2023 14:27:14 -0700 From: Kees Cook To: Marco Elver Cc: Andrew Morton , Guenter Roeck , Peter Zijlstra , Mark Rutland , Steven Rostedt , Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Nathan Chancellor , Nick Desaulniers , Tom Rix , Miguel Ojeda , Sami Tolvanen , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Dmitry Vyukov , Alexander Potapenko , kasan-dev@googlegroups.com, linux-toolchains@vger.kernel.org Subject: Re: [PATCH v3 3/3] list_debug: Introduce CONFIG_DEBUG_LIST_MINIMAL Message-ID: <202308081424.1DC7AA4AE3@keescook> References: <20230808102049.465864-1-elver@google.com> <20230808102049.465864-3-elver@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230808102049.465864-3-elver@google.com> X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 08, 2023 at 12:17:27PM +0200, Marco Elver wrote: > Numerous production kernel configs (see [1, 2]) are choosing to enable > CONFIG_DEBUG_LIST, which is also being recommended by KSPP for hardened > configs [3]. The feature has never been designed with performance in > mind, yet common list manipulation is happening across hot paths all > over the kernel. > > Introduce CONFIG_DEBUG_LIST_MINIMAL, which performs list pointer > checking inline, and only upon list corruption delegates to the > reporting slow path. I'd really like to get away from calling this "DEBUG", since it's used more for hardening (CONFIG_LIST_HARDENED?). Will Deacon spent some time making this better a while back, but the series never landed. Do you have a bit of time to look through it? https://github.com/KSPP/linux/issues/10 https://lore.kernel.org/lkml/20200324153643.15527-1-will@kernel.org/ -Kees -- Kees Cook