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-randconfig-r013-20210620 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project e1adf90826a57b674eee79b071fb46c1f5683cd0) 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 # install arm cross compiling tool for clang build # apt-get install binutils-arm-linux-gnueabi # 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=clang 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 function '__div0' [-Wmissing-prototypes] asmlinkage void __div0(void) ^ arch/arm/boot/compressed/misc.c:126:12: note: declare 'static' if the function is not intended to be used outside of this translation unit asmlinkage void __div0(void) ^ static arch/arm/boot/compressed/misc.c:133:6: warning: no previous prototype for function '__stack_chk_fail' [-Wmissing-prototypes] void __stack_chk_fail(void) ^ arch/arm/boot/compressed/misc.c:133:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void __stack_chk_fail(void) ^ static arch/arm/boot/compressed/misc.c:142:1: warning: no previous prototype for function 'decompress_kernel' [-Wmissing-prototypes] decompress_kernel(unsigned long output_start, unsigned long free_mem_ptr_p, ^ arch/arm/boot/compressed/misc.c:141:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void ^ static void fortify_warn_write(const char *func, size_t buffer_size, size_t write_size) ^ arch/arm/boot/compressed/misc.c:164:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void fortify_warn_write(const char *func, size_t buffer_size, size_t write_size) ^ static arch/arm/boot/compressed/misc.c:169:6: warning: no previous prototype for function 'fortify_panic' [-Wmissing-prototypes] void fortify_panic(const char *name) ^ arch/arm/boot/compressed/misc.c:169:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void fortify_panic(const char *name) ^ static 5 warnings generated. 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