From: Kees Cook keescook@chromium.org

Upstream commit: 69d0db01e210 ("ubsan: remove CONFIG_UBSAN_OBJECT_SIZE")

The object-size sanitizer is redundant to -Warray-bounds, and inappropriately performs its checks at run-time when all information needed for the evaluation is available at compile-time, making it quite difficult to use:

https://bugzilla.kernel.org/show_bug.cgi?id=214861

This run-time object-size checks also trigger false-positive errors, like the below, that make it quite difficult to test stable kernels in test automations like syzkaller:

https://syzkaller.appspot.com/text?tag=Error&x=12b3aac3700000

With -Warray-bounds almost enabled globally, it doesn't make sense to keep this around.

Link: https://lkml.kernel.org/r/20211203235346.110809-1-keescook@chromium.org Signed-off-by: Kees Cook keescook@chromium.org Reviewed-by: Marco Elver elver@google.com Cc: Masahiro Yamada masahiroy@kernel.org Cc: Michal Marek michal.lkml@markovi.net Cc: Nick Desaulniers ndesaulniers@google.com Cc: Nathan Chancellor nathan@kernel.org Cc: Andrey Ryabinin ryabinin.a.a@gmail.com Cc: "Peter Zijlstra (Intel)" peterz@infradead.org Cc: Stephen Rothwell sfr@canb.auug.org.au Cc: Arnd Bergmann arnd@arndb.de Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Tadeusz Struk tadeusz.struk@linaro.org --- lib/test_ubsan.c | 11 ----------- scripts/Makefile.ubsan | 1 - 2 files changed, 12 deletions(-)

diff --git a/lib/test_ubsan.c b/lib/test_ubsan.c index 9ea10adf7a66..b1d0a6ecfe1b 100644 --- a/lib/test_ubsan.c +++ b/lib/test_ubsan.c @@ -89,16 +89,6 @@ static void test_ubsan_misaligned_access(void) *ptr = val; }

-static void test_ubsan_object_size_mismatch(void) -{ - /* "((aligned(8)))" helps this not into be misaligned for ptr-access. */ - volatile int val __aligned(8) = 4; - volatile long long *ptr, val2; - - ptr = (long long *)&val; - val2 = *ptr; -} - static const test_ubsan_fp test_ubsan_array[] = { test_ubsan_add_overflow, test_ubsan_sub_overflow, @@ -110,7 +100,6 @@ static const test_ubsan_fp test_ubsan_array[] = { test_ubsan_load_invalid_value, //test_ubsan_null_ptr_deref, /* exclude it because there is a crash */ test_ubsan_misaligned_access, - test_ubsan_object_size_mismatch, };

static int __init test_ubsan_init(void) diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan index 9716dab06bc7..2156e18391a3 100644 --- a/scripts/Makefile.ubsan +++ b/scripts/Makefile.ubsan @@ -23,7 +23,6 @@ ifdef CONFIG_UBSAN_MISC CFLAGS_UBSAN += $(call cc-option, -fsanitize=integer-divide-by-zero) CFLAGS_UBSAN += $(call cc-option, -fsanitize=unreachable) CFLAGS_UBSAN += $(call cc-option, -fsanitize=signed-integer-overflow) - CFLAGS_UBSAN += $(call cc-option, -fsanitize=object-size) CFLAGS_UBSAN += $(call cc-option, -fsanitize=bool) CFLAGS_UBSAN += $(call cc-option, -fsanitize=enum) endif