[linux-next:master 6391/9634] include/linux/ucopysize.h:47:25: error: call to '__bad_copy_to' declared with attribute error: copy destination size is too small

[linux-next:master 6391/9634] include/linux/ucopysize.h:47:25: error: call to '__bad_copy_to' declared with attribute error: copy destination size is too small

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   0a2f889128969dab41861b6e40111aa03dc57014
commit: 808aac63e2bdf9bae08485e072bf3d317a18acbf [6391/9634] uaccess: Introduce ucopysize.h
config: i386-buildonly-randconfig-001-20250308 (https://download.01.org/0day-ci/archive/20250308/202503081120.jyUyb28m-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250308/202503081120.jyUyb28m-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/202503081120.jyUyb28m-lkp@intel.com/

Note: the linux-next/master HEAD 0a2f889128969dab41861b6e40111aa03dc57014 builds fine.
      It may have been fixed somewhere.

All errors (new ones prefixed by >>):

   In file included from include/linux/uaccess.h:10,
                    from include/linux/sched/task.h:13,
                    from include/linux/sched/signal.h:9,
                    from include/linux/rcuwait.h:6,
                    from include/linux/percpu-rwsem.h:7,
                    from include/linux/fs.h:33,
                    from drivers/misc/ntsync.c:11:
   In function 'check_copy_size',
       inlined from 'copy_from_user' at include/linux/uaccess.h:207:7,
       inlined from 'setup_wait' at drivers/misc/ntsync.c:890:6:
>> include/linux/ucopysize.h:47:25: error: call to '__bad_copy_to' declared with attribute error: copy destination size is too small
      47 |                         __bad_copy_to();
         |                         ^~~~~~~~~~~~~~~


vim +/__bad_copy_to +47 include/linux/ucopysize.h

    36	
    37	static __always_inline __must_check bool
    38	check_copy_size(const void *addr, size_t bytes, bool is_source)
    39	{
    40		int sz = __builtin_object_size(addr, 0);
    41		if (unlikely(sz >= 0 && sz < bytes)) {
    42			if (!__builtin_constant_p(bytes))
    43				copy_overflow(sz, bytes);
    44			else if (is_source)
    45				__bad_copy_from();
    46			else
  > 47				__bad_copy_to();
    48			return false;
    49		}
    50		if (WARN_ON_ONCE(bytes > INT_MAX))
    51			return false;
    52		check_object_size(addr, bytes, is_source);
    53		return true;
    54	}
    55	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [linux-next:master 6391/9634] include/linux/ucopysize.h:47:25: error: call to '__bad_copy_to' declared with attribute error: copy destination size is too small

[Kees Cook]

On Sat, Mar 08, 2025 at 11:39:28AM +0800, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   0a2f889128969dab41861b6e40111aa03dc57014
> commit: 808aac63e2bdf9bae08485e072bf3d317a18acbf [6391/9634] uaccess: Introduce ucopysize.h
> config: i386-buildonly-randconfig-001-20250308 (https://download.01.org/0day-ci/archive/20250308/202503081120.jyUyb28m-lkp@intel.com/config)
> compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250308/202503081120.jyUyb28m-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/202503081120.jyUyb28m-lkp@intel.com/
> 
> Note: the linux-next/master HEAD 0a2f889128969dab41861b6e40111aa03dc57014 builds fine.
>       It may have been fixed somewhere.
> 
> All errors (new ones prefixed by >>):
> 
>    In file included from include/linux/uaccess.h:10,
>                     from include/linux/sched/task.h:13,
>                     from include/linux/sched/signal.h:9,
>                     from include/linux/rcuwait.h:6,
>                     from include/linux/percpu-rwsem.h:7,
>                     from include/linux/fs.h:33,
>                     from drivers/misc/ntsync.c:11:
>    In function 'check_copy_size',
>        inlined from 'copy_from_user' at include/linux/uaccess.h:207:7,
>        inlined from 'setup_wait' at drivers/misc/ntsync.c:890:6:
> >> include/linux/ucopysize.h:47:25: error: call to '__bad_copy_to' declared with attribute error: copy destination size is too small
>       47 |                         __bad_copy_to();
>          |                         ^~~~~~~~~~~~~~~

It looks like this is an old error that just changed because the name of
the header containing __bad_copy_to changed.

Regardless, I can't reproduce this with GCC 12.3 (Ubuntu). I'm getting a
build image for Debian 12 (GCC 12.2) built to see if there is a
difference...


-- 
Kees Cook