diff options
| author | Kees Cook <keescook@chromium.org> | 2022-10-24 23:11:25 +0300 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2022-11-02 12:39:27 -0700 |
| commit | 4b21d25bf519c9487935a664886956bb18f04f6d (patch) | |
| tree | ea067b7ddbc65e7285aa22389cb020c9fcb0fb54 /include/linux/compiler.h | |
| parent | 6dd142d9013ca82155d0c069434c60a0d5755ec0 (diff) | |
overflow: Introduce overflows_type() and castable_to_type()
Implement a robust overflows_type() macro to test if a variable or
constant value would overflow another variable or type. This can be
used as a constant expression for static_assert() (which requires a
constant expression[1][2]) when used on constant values. This must be
constructed manually, since __builtin_add_overflow() does not produce
a constant expression[3].
Additionally adds castable_to_type(), similar to __same_type(), but for
checking if a constant value would overflow if cast to a given type.
Add unit tests for overflows_type(), __same_type(), and castable_to_type()
to the existing KUnit "overflow" test:
[16:03:33] ================== overflow (21 subtests) ==================
...
[16:03:33] [PASSED] overflows_type_test
[16:03:33] [PASSED] same_type_test
[16:03:33] [PASSED] castable_to_type_test
[16:03:33] ==================== [PASSED] overflow =====================
[16:03:33] ============================================================
[16:03:33] Testing complete. Ran 21 tests: passed: 21
[16:03:33] Elapsed time: 24.022s total, 0.002s configuring, 22.598s building, 0.767s running
[1] https://en.cppreference.com/w/c/language/_Static_assert
[2] C11 standard (ISO/IEC 9899:2011): 6.7.10 Static assertions
[3] https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html
6.56 Built-in Functions to Perform Arithmetic with Overflow Checking
Built-in Function: bool __builtin_add_overflow (type1 a, type2 b,
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Tom Rix <trix@redhat.com>
Cc: Daniel Latypov <dlatypov@google.com>
Cc: Vitor Massaru Iha <vitor@massaru.org>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: linux-hardening@vger.kernel.org
Cc: llvm@lists.linux.dev
Co-developed-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221024201125.1416422-1-gwan-gyeong.mun@intel.com
Diffstat (limited to 'include/linux/compiler.h')
| -rw-r--r-- | include/linux/compiler.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 973a1bfd7ef5..947a60b801db 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -236,6 +236,7 @@ static inline void *offset_to_ptr(const int *off) * bool and also pointer types. */ #define is_signed_type(type) (((type)(-1)) < (__force type)1) +#define is_unsigned_type(type) (!is_signed_type(type)) /* * This is needed in functions which generate the stack canary, see |