Gain coverage for pointer wrap-around checking. Adds support for -fsanitize=pointer-overflow, and introduces the __pointer_wrap function attribute to match the signed and unsigned attributes. Also like the others, it is currently disabled under CONFIG_COMPILE_TEST.
Cc: Andrew Morton <a...@linux-foundation.org> Cc: Masahiro Yamada <masahi...@kernel.org> Cc: Nathan Chancellor <nat...@kernel.org> Cc: Nicolas Schier <nico...@fjasle.eu> Cc: linux-kbu...@vger.kernel.org Signed-off-by: Kees Cook <keesc...@chromium.org> --- include/linux/compiler_types.h | 7 ++++++- lib/Kconfig.ubsan | 8 ++++++++ lib/test_ubsan.c | 33 +++++++++++++++++++++++++++++++++ lib/ubsan.c | 21 +++++++++++++++++++++ lib/ubsan.h | 1 + scripts/Makefile.ubsan | 1 + 6 files changed, 70 insertions(+), 1 deletion(-) diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index e585614f3152..e65ce55046fd 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -293,12 +293,17 @@ struct ftrace_likely_data { #else # define __unsigned_wrap #endif +#ifdef CONFIG_UBSAN_POINTER_WRAP +# define __pointer_wrap __attribute__((no_sanitize("pointer-overflow"))) +#else +# define __pointer_wrap +#endif /* Section for code which can't be instrumented at all */ #define __noinstr_section(section) \ noinline notrace __attribute((__section__(section))) \ __no_kcsan __no_sanitize_address __no_profile __no_sanitize_coverage \ - __no_sanitize_memory __signed_wrap __unsigned_wrap + __no_sanitize_memory __signed_wrap __unsigned_wrap __pointer_wrap #define noinstr __noinstr_section(".noinstr.text") diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan index a7003e5bd2a1..04222a6d7fd9 100644 --- a/lib/Kconfig.ubsan +++ b/lib/Kconfig.ubsan @@ -135,6 +135,14 @@ config UBSAN_UNSIGNED_WRAP for wrap-around of any arithmetic operations with unsigned integers. This currently causes x86 to fail to boot. +config UBSAN_POINTER_WRAP + bool "Perform checking for pointer arithmetic wrap-around" + depends on !COMPILE_TEST + depends on $(cc-option,-fsanitize=pointer-overflow) + help + This option enables -fsanitize=pointer-overflow which checks + for wrap-around of any arithmetic operations with pointers. + config UBSAN_BOOL bool "Perform checking for non-boolean values used as boolean" default UBSAN diff --git a/lib/test_ubsan.c b/lib/test_ubsan.c index 84d8092d6c32..1cc049b3ef34 100644 --- a/lib/test_ubsan.c +++ b/lib/test_ubsan.c @@ -56,6 +56,36 @@ static void test_ubsan_negate_overflow(void) val = -val; } +static void test_ubsan_pointer_overflow_add(void) +{ + volatile void *top = (void *)ULONG_MAX; + + UBSAN_TEST(CONFIG_UBSAN_POINTER_WRAP); + top += 2; +} + +static void test_ubsan_pointer_overflow_sub(void) +{ + volatile void *bottom = (void *)1; + + UBSAN_TEST(CONFIG_UBSAN_POINTER_WRAP); + bottom -= 3; +} + +struct ptr_wrap { + int a; + int b; +}; + +static void test_ubsan_pointer_overflow_mul(void) +{ + volatile struct ptr_wrap *half = (void *)(ULONG_MAX - 128); + volatile int bump = 128; + + UBSAN_TEST(CONFIG_UBSAN_POINTER_WRAP); + half += bump; +} + static void test_ubsan_divrem_overflow(void) { volatile int val = 16; @@ -139,6 +169,9 @@ static const test_ubsan_fp test_ubsan_array[] = { test_ubsan_sub_overflow, test_ubsan_mul_overflow, test_ubsan_negate_overflow, + test_ubsan_pointer_overflow_add, + test_ubsan_pointer_overflow_sub, + test_ubsan_pointer_overflow_mul, test_ubsan_shift_out_of_bounds, test_ubsan_out_of_bounds, test_ubsan_load_invalid_value, diff --git a/lib/ubsan.c b/lib/ubsan.c index 5fc107f61934..d49580ff6aea 100644 --- a/lib/ubsan.c +++ b/lib/ubsan.c @@ -289,6 +289,27 @@ void __ubsan_handle_negate_overflow(void *_data, void *old_val) } EXPORT_SYMBOL(__ubsan_handle_negate_overflow); +void __ubsan_handle_pointer_overflow(void *_data, void *lhs, void *rhs) +{ + struct overflow_data *data = _data; + unsigned long before = (unsigned long)lhs; + unsigned long after = (unsigned long)rhs; + + if (suppress_report(&data->location)) + return; + + ubsan_prologue(&data->location, "pointer-overflow"); + + if (after == 0) + pr_err("overflow wrapped to NULL\n"); + else if (after < before) + pr_err("overflow wrap-around\n"); + else + pr_err("underflow wrap-around\n"); + + ubsan_epilogue(); +} +EXPORT_SYMBOL(__ubsan_handle_pointer_overflow); void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs) { diff --git a/lib/ubsan.h b/lib/ubsan.h index 0abbbac8700d..5dd27923b78b 100644 --- a/lib/ubsan.h +++ b/lib/ubsan.h @@ -128,6 +128,7 @@ void __ubsan_handle_add_overflow(void *data, void *lhs, void *rhs); void __ubsan_handle_sub_overflow(void *data, void *lhs, void *rhs); void __ubsan_handle_mul_overflow(void *data, void *lhs, void *rhs); void __ubsan_handle_negate_overflow(void *_data, void *old_val); +void __ubsan_handle_pointer_overflow(void *_data, void *lhs, void *rhs); void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs); void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, void *ptr); void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr); diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan index 7b2f3d554c59..df4ccf063f67 100644 --- a/scripts/Makefile.ubsan +++ b/scripts/Makefile.ubsan @@ -10,6 +10,7 @@ ubsan-cflags-$(CONFIG_UBSAN_DIV_ZERO) += -fsanitize=integer-divide-by-zero ubsan-cflags-$(CONFIG_UBSAN_UNREACHABLE) += -fsanitize=unreachable ubsan-cflags-$(CONFIG_UBSAN_SIGNED_WRAP) += -fsanitize=signed-integer-overflow ubsan-cflags-$(CONFIG_UBSAN_UNSIGNED_WRAP) += -fsanitize=unsigned-integer-overflow +ubsan-cflags-$(CONFIG_UBSAN_POINTER_WRAP) += -fsanitize=pointer-overflow ubsan-cflags-$(CONFIG_UBSAN_BOOL) += -fsanitize=bool ubsan-cflags-$(CONFIG_UBSAN_ENUM) += -fsanitize=enum ubsan-cflags-$(CONFIG_UBSAN_TRAP) += $(call cc-option,-fsanitize-trap=undefined,-fsanitize-undefined-trap-on-error) -- 2.34.1