Re: [PATCH 1/3] ubsan/overflow: Rework integer overflow sanitizer option to turn on everything

[Kees Cook <kees@kernel.org>]

On Mon, Mar 10, 2025 at 10:54:12AM +0800, kernel test robot wrote:
> Hi Kees,
> 
> kernel test robot noticed the following build warnings:
> 
> [auto build test WARNING on kees/for-next/hardening]
> [also build test WARNING on masahiroy-kbuild/for-next masahiroy-kbuild/fixes kees/for-next/pstore linus/master v6.14-rc6 next-20250307]
> [cannot apply to kees/for-next/kspp]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Kees-Cook/ubsan-overflow-Rework-integer-overflow-sanitizer-option-to-turn-on-everything/20250307-122130
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/hardening
> patch link:    https://lore.kernel.org/r/20250307041914.937329-1-kees%40kernel.org
> patch subject: [PATCH 1/3] ubsan/overflow: Rework integer overflow sanitizer option to turn on everything
> config: s390-randconfig-r112-20250310 (https://download.01.org/0day-ci/archive/20250310/202503101035.rpwDzqYD-lkp@intel.com/config)
> compiler: s390-linux-gcc (GCC) 14.2.0
> reproduce: (https://download.01.org/0day-ci/archive/20250310/202503101035.rpwDzqYD-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202503101035.rpwDzqYD-lkp@intel.com/
> 
> sparse warnings: (new ones prefixed by >>)
> >> lib/test_ubsan.c:62:16: sparse: sparse: cast truncates bits from constant value (7fffffffffffffff becomes ffffffff)
>    lib/test_ubsan.c:72:18: sparse: sparse: shift count is negative (-1)

Can we exclude certain source files from sparse? This whole file is
basically an endless series of intentionally bad operations. :)

-Kees

> 
> vim +62 lib/test_ubsan.c
> 
>     55	
>     56	static void test_ubsan_truncate_signed(void)
>     57	{
>     58		volatile long val = LONG_MAX;
>     59		volatile int val2 = 0;
>     60	
>     61		UBSAN_TEST(CONFIG_UBSAN_INTEGER_WRAP);
>   > 62		val2 = val;
>     63	}
>     64	
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki

-- 
Kees Cook