tree: https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git kspp/memcpy/next-20210618/v0.192314 head: bbcfcdcf3881ef6f9ae1b1b8e0ddf03da30c5aad commit: 37bd2f986fbed8a837e7657c7a44d588e79c5aad [57/90] fortify: Detect struct member overflows in memcpy() config: arm-spear13xx_defconfig (attached as .config) compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0 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://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?id... git remote add kees https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git git fetch --no-tags kees kspp/memcpy/next-20210618/v0.192314 git checkout 37bd2f986fbed8a837e7657c7a44d588e79c5aad # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): arch/arm/boot/compressed/misc.c:126:17: warning: no previous prototype for '__div0' [-Wmissing-prototypes] 126 | asmlinkage void __div0(void) | ^~~~~~ arch/arm/boot/compressed/misc.c:133:6: warning: no previous prototype for '__stack_chk_fail' [-Wmissing-prototypes] 133 | void __stack_chk_fail(void) | ^~~~~~~~~~~~~~~~ arch/arm/boot/compressed/misc.c:142:1: warning: no previous prototype for 'decompress_kernel' [-Wmissing-prototypes] 142 | decompress_kernel(unsigned long output_start, unsigned long free_mem_ptr_p, | ^~~~~~~~~~~~~~~~~ 164 | void fortify_warn_write(const char *func, size_t buffer_size, size_t write_size) | ^~~~~~~~~~~~~~~~~~ arch/arm/boot/compressed/misc.c:169:6: warning: no previous prototype for 'fortify_panic' [-Wmissing-prototypes] 169 | void fortify_panic(const char *name) | ^~~~~~~~~~~~~ vim +/fortify_warn_write +164 arch/arm/boot/compressed/misc.c 163 165 { 166 putstr("warning: detected buffer overflow\n"); 167 } 168 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org