Under some pathological 32-bit configs, the shift overflow KUnit tests
create huge stack frames. Split up the function to avoid this,
separating by rough shift overflow cases.
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Daniel Latypov <dlatypov@google.com>
Cc: Vitor Massaru Iha <vitor@massaru.org>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/202208301850.iuv9VwA8-lkp@intel.com
Acked-by: Daniel Latypov <dlatypov@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
When the check_[op]_overflow() helpers were introduced, all arguments
were required to be the same type to make the fallback macros simpler.
However, now that the fallback macros have been removed[1], it is fine
to allow mixed types, which makes using the helpers much more useful,
as they can be used to test for type-based overflows (e.g. adding two
large ints but storing into a u8), as would be handy in the drm core[2].
Remove the restriction, and add additional self-tests that exercise
some of the mixed-type overflow cases, and double-check for accidental
macro side-effects.
[1] https://git.kernel.org/linus/4eb6bd55cfb22ffc20652732340c4962f3ac9a91
[2] https://lore.kernel.org/lkml/20220824084514.2261614-2-gwan-gyeong.mun@intel.com
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: linux-hardening@vger.kernel.org
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Tested-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
The 64-bit overflow tests will trigger 64-bit division on 32-bit hosts,
which is not currently used anywhere in the kernel, and tickles bugs
in at least Clang 13 and earlier:
https://github.com/ClangBuiltLinux/linux/issues/1636
In reality, there shouldn't be a reason to not build the 64-bit test
cases on 32-bit systems, so these #ifdefs can be removed once the minimum
Clang version reaches 13.
In the meantime, silence W=1 warnings given by the current code:
../lib/overflow_kunit.c:191:19: warning: 's64_tests' defined but not used [-Wunused-const-variable=]
191 | DEFINE_TEST_ARRAY(s64) = {
| ^~~
../lib/overflow_kunit.c:24:11: note: in definition of macro 'DEFINE_TEST_ARRAY'
24 | } t ## _tests[]
| ^
../lib/overflow_kunit.c:94:19: warning: 'u64_tests' defined but not used [-Wunused-const-variable=]
94 | DEFINE_TEST_ARRAY(u64) = {
| ^~~
../lib/overflow_kunit.c:24:11: note: in definition of macro 'DEFINE_TEST_ARRAY'
24 | } t ## _tests[]
| ^
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/202205110324.7GrtxG8u-lkp@intel.com
Fixes: 455a35a6cd ("lib: add runtime test of check_*_overflow functions")
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Vitor Massaru Iha <vitor@massaru.org>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Tested-by: Daniel Latypov <dlatypov@google.com>
Link: https://lore.kernel.org/lkml/CAGS_qxokQAjQRip2vPi80toW7hmBnXf=KMTNT51B1wuDqSZuVQ@mail.gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
