Hi Takashi, I love your patch! Yet something to improve: [auto build test ERROR on tiwai-sound/for-next] [also build test ERROR on next-20211025] [cannot apply to v5.15-rc6] [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] url: https://github.com/0day-ci/linux/commits/Takashi-Sakamoto/ALSA-firewire-m... base: https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git for-next config: arc-randconfig-r043-20211020 (attached as .config) compiler: arc-elf-gcc (GCC) 11.2.0 reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # https://github.com/0day-ci/linux/commit/0105a381c2c6677118fca8f30b96778d5... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Takashi-Sakamoto/ALSA-firewire-motu-fix-invalid-memory-access-when-operating-hwdep-character-device/20211020-122834 git checkout 0105a381c2c6677118fca8f30b96778d590e2173 # save the attached .config to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=arc SHELL=/bin/bash sound/firewire/motu/ If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): In file included from include/asm-generic/current.h:5, from arch/arc/include/asm/current.h:20, from include/linux/sched.h:12, from include/linux/ratelimit.h:6, from include/linux/dev_printk.h:16, from include/linux/device.h:15, from sound/firewire/motu/motu.h:11, from sound/firewire/motu/motu-hwdep.c:17: In function 'check_copy_size', inlined from 'copy_to_user' at include/linux/uaccess.h:199:6, inlined from 'copy_dsp_event_to_user' at sound/firewire/motu/motu-hwdep.c:49:7, inlined from 'hwdep_read' at sound/firewire/motu/motu-hwdep.c:101:11: 211 | __bad_copy_from(); | ^~~~~~~~~~~~~~~~~ vim +/__bad_copy_from +211 include/linux/thread_info.h b0377fedb65280 Al Viro 2017-06-29 202 9dd819a15162f8 Kees Cook 2019-09-25 203 static __always_inline __must_check bool b0377fedb65280 Al Viro 2017-06-29 204 check_copy_size(const void *addr, size_t bytes, bool is_source) b0377fedb65280 Al Viro 2017-06-29 205 { b0377fedb65280 Al Viro 2017-06-29 206 int sz = __compiletime_object_size(addr); b0377fedb65280 Al Viro 2017-06-29 207 if (unlikely(sz >= 0 && sz < bytes)) { b0377fedb65280 Al Viro 2017-06-29 208 if (!__builtin_constant_p(bytes)) b0377fedb65280 Al Viro 2017-06-29 209 copy_overflow(sz, bytes); b0377fedb65280 Al Viro 2017-06-29 210 else if (is_source) b0377fedb65280 Al Viro 2017-06-29 @211 __bad_copy_from(); b0377fedb65280 Al Viro 2017-06-29 212 else b0377fedb65280 Al Viro 2017-06-29 213 __bad_copy_to(); b0377fedb65280 Al Viro 2017-06-29 214 return false; b0377fedb65280 Al Viro 2017-06-29 215 } 6d13de1489b6bf Kees Cook 2019-12-04 216 if (WARN_ON_ONCE(bytes > INT_MAX)) 6d13de1489b6bf Kees Cook 2019-12-04 217 return false; b0377fedb65280 Al Viro 2017-06-29 218 check_object_size(addr, bytes, is_source); b0377fedb65280 Al Viro 2017-06-29 219 return true; b0377fedb65280 Al Viro 2017-06-29 220 } b0377fedb65280 Al Viro 2017-06-29 221 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org