[PATCH 5.16 273/285] ubsan: remove CONFIG_UBSAN_OBJECT_SIZE

Greg Kroah-Hartman
2022-04-12T08:11:08Z

From: Kees Cook <keescook@chromium.org>

commit 69d0db01e210e07fe915e5da91b54a867cda040f upstream.

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

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>
Cc: Tadeusz Struk <tadeusz.struk@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
lib/Kconfig.ubsan | 13 -------------
lib/test_ubsan.c | 22 ----------------------
scripts/Makefile.ubsan | 1 -
3 files changed, 36 deletions(-)

--- a/lib/Kconfig.ubsan
+++ b/lib/Kconfig.ubsan
@@ -112,19 +112,6 @@ config UBSAN_UNREACHABLE
This option enables -fsanitize=unreachable which checks for control
flow reaching an expected-to-be-unreachable position.

-config UBSAN_OBJECT_SIZE
- bool "Perform checking for accesses beyond the end of objects"
- default UBSAN
- # gcc hugely expands stack usage with -fsanitize=object-size
- # https://lore.kernel.org/lkml/CAHk-=wjPasyJrDuwDnpHJS2TuQfExwe=px-SzLeN8GFMAQJPmQ@mail.gmail.com/
- depends on !CC_IS_GCC
- depends on $(cc-option,-fsanitize=object-size)
- help
- This option enables -fsanitize=object-size which checks for accesses
- beyond the end of objects where the optimizer can determine both the
- object being operated on and its size, usually seen with bad downcasts,
- or access to struct members from NULL pointers.
-
config UBSAN_BOOL
bool "Perform checking for non-boolean values used as boolean"
default UBSAN
--- a/lib/test_ubsan.c
+++ b/lib/test_ubsan.c
@@ -79,15 +79,6 @@ static void test_ubsan_load_invalid_valu
eval2 = eval;
}

-static void test_ubsan_null_ptr_deref(void)
-{
- volatile int *ptr = NULL;
- int val;
-
- UBSAN_TEST(CONFIG_UBSAN_OBJECT_SIZE);
- val = *ptr;
-}
-
static void test_ubsan_misaligned_access(void)
{
volatile char arr[5] __aligned(4) = {1, 2, 3, 4, 5};
@@ -98,29 +89,16 @@ static void test_ubsan_misaligned_access
*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;
-
- UBSAN_TEST(CONFIG_UBSAN_OBJECT_SIZE);
- ptr = (long long *)&val;
- val2 = *ptr;
-}
-
static const test_ubsan_fp test_ubsan_array[] = {
test_ubsan_shift_out_of_bounds,
test_ubsan_out_of_bounds,
test_ubsan_load_invalid_value,
test_ubsan_misaligned_access,
- test_ubsan_object_size_mismatch,
};

/* Excluded because they Oops the module. */
static const test_ubsan_fp skip_ubsan_array[] = {
test_ubsan_divrem_overflow,
- test_ubsan_null_ptr_deref,
};

static int __init test_ubsan_init(void)
--- a/scripts/Makefile.ubsan
+++ b/scripts/Makefile.ubsan
@@ -8,7 +8,6 @@ ubsan-cflags-$(CONFIG_UBSAN_LOCAL_BOUNDS
ubsan-cflags-$(CONFIG_UBSAN_SHIFT) += -fsanitize=shift
ubsan-cflags-$(CONFIG_UBSAN_DIV_ZERO) += -fsanitize=integer-divide-by-zero
ubsan-cflags-$(CONFIG_UBSAN_UNREACHABLE) += -fsanitize=unreachable
-ubsan-cflags-$(CONFIG_UBSAN_OBJECT_SIZE) += -fsanitize=object-size
ubsan-cflags-$(CONFIG_UBSAN_BOOL) += -fsanitize=bool
ubsan-cflags-$(CONFIG_UBSAN_ENUM) += -fsanitize=enum
ubsan-cflags-$(CONFIG_UBSAN_TRAP) += -fsanitize-undefined-trap-on-error