Re: [linux-next:master 4186/4898] debug.c:undefined reference to `__ubsan_handle_divrem_overflow'

[Kees Cook <keescook@chromium.org>]

On Thu, Feb 08, 2024 at 06:00:13AM +0800, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   2ae0a045e6814c8c1d676d6153c605a65746aa29
> commit: 5084a4cd510f887a4fcc9f3386de1fbea698c7c4 [4186/4898] ubsan: reintroduce signed overflow sanitizer
> config: s390-randconfig-r063-20240207 (https://download.01.org/0day-ci/archive/20240208/202402080538.FNTaeLJO-lkp@intel.com/config)
> compiler: s390-linux-gcc (GCC) 13.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240208/202402080538.FNTaeLJO-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/202402080538.FNTaeLJO-lkp@intel.com/
> 
> Note: the linux-next/master HEAD 2ae0a045e6814c8c1d676d6153c605a65746aa29 builds fine.
>       It may have been fixed somewhere.
> 
> All errors (new ones prefixed by >>):
> 
>    s390-linux-ld: arch/s390/kernel/debug.o: in function `debug_output':
> >> debug.c:(.text+0x17ea): undefined reference to `__ubsan_handle_divrem_overflow'

I'm not able to reproduce these warnings. I'm using the config above and
s390x-linux-gnu-gcc (Ubuntu 13.2.0-4ubuntu3) 13.2.0

I would expect adding this to arch/s390/kernel/Makefile would fix it:

UBSAN_SANITIZE_debug.o                := n

But I can't meaningfully verify the fix...

-- 
Kees Cook