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[34.77.222.49]) by smtp.gmail.com with ESMTPSA id c14sm24062347wrv.12.2020.09.22.00.43.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 22 Sep 2020 00:43:34 -0700 (PDT) From: George-Aurelian Popescu To: masahiroy@kernel.org, michal.lkml@markovi.net, natechancellor@gmail.com, ndesaulniers@google.com, keescook@chromium.org, akpm@linux-foundation.org, elver@google.com, dvyukov@google.com Cc: peterz@infradead.org, arnd@arndb.de, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, dbrazdil@google.com, George Popescu Subject: [PATCH v3] ubsan: introducing CONFIG_UBSAN_LOCAL_BOUNDS for Clang Date: Tue, 22 Sep 2020 07:43:30 +0000 Message-Id: <20200922074330.2549523-1-georgepope@google.com> X-Mailer: git-send-email 2.28.0.681.g6f77f65b4e-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: George Popescu When the kernel is compiled with Clang, -fsanitize=bounds expands to -fsanitize=array-bounds and -fsanitize=local-bounds. Enabling -fsanitize=local-bounds with Clang has the unfortunate side-effect of inserting traps; this goes back to its original intent, which was as a hardening and not a debugging feature [1]. The same feature made its way into -fsanitize=bounds, but the traps remained. For that reason, -fsanitize=bounds was split into 'array-bounds' and 'local-bounds' [2]. Since 'local-bounds' doesn't behave like a normal sanitizer, enable it with Clang only if trapping behaviour was requested by CONFIG_UBSAN_TRAP=y. Add the UBSAN_BOUNDS_LOCAL config to Kconfig.ubsan to enable the 'local-bounds' option by default when UBSAN_TRAP is enabled. [1] http://lists.llvm.org/pipermail/llvm-dev/2012-May/049972.html [2] http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20131021/091536.html Suggested-by: Marco Elver Reviewed-by: David Brazdil Reviewed-by: Marco Elver Signed-off-by: George Popescu --- v2: changed the name of the config, in Kconfig, to UBSAN_LOCAL_BOUNDS --- v3: added Reviewed-by tag --- lib/Kconfig.ubsan | 14 ++++++++++++++ scripts/Makefile.ubsan | 10 +++++++++- 2 files changed, 23 insertions(+), 1 deletion(-) diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan index 774315de555a..58f8d03d037b 100644 --- a/lib/Kconfig.ubsan +++ b/lib/Kconfig.ubsan @@ -47,6 +47,20 @@ config UBSAN_BOUNDS to the {str,mem}*cpy() family of functions (that is addressed by CONFIG_FORTIFY_SOURCE). +config UBSAN_LOCAL_BOUNDS + bool "Perform array local bounds checking" + depends on UBSAN_TRAP + depends on CC_IS_CLANG + depends on !UBSAN_KCOV_BROKEN + help + This option enables -fsanitize=local-bounds which traps when an + exception/error is detected. Therefore, it should be enabled only + if trapping is expected. + Enabling this option detects errors due to accesses through a + pointer that is derived from an object of a statically-known size, + where an added offset (which may not be known statically) is + out-of-bounds. + config UBSAN_MISC bool "Enable all other Undefined Behavior sanity checks" default UBSAN diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan index 27348029b2b8..4e3fff0745e8 100644 --- a/scripts/Makefile.ubsan +++ b/scripts/Makefile.ubsan @@ -4,7 +4,15 @@ ifdef CONFIG_UBSAN_ALIGNMENT endif ifdef CONFIG_UBSAN_BOUNDS - CFLAGS_UBSAN += $(call cc-option, -fsanitize=bounds) + ifdef CONFIG_CC_IS_CLANG + CFLAGS_UBSAN += -fsanitize=array-bounds + else + CFLAGS_UBSAN += $(call cc-option, -fsanitize=bounds) + endif +endif + +ifdef CONFIG_UBSAN_LOCAL_BOUNDS + CFLAGS_UBSAN += -fsanitize=local-bounds endif ifdef CONFIG_UBSAN_MISC -- 2.28.0.681.g6f77f65b4e-goog