tree: https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git kspp/memcpy/next-20210621/v0 head: 711a2c0c23d479d212e8d80f5dcaaf267162c8de commit: bcd1e43915effef8bcc583726d55e91780ad7a63 [76/86] fortify: Detect struct member overflows in memset() config: mips-randconfig-r011-20210621 (attached as .config) compiler: mips-linux-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-20210621/v0 git checkout bcd1e43915effef8bcc583726d55e91780ad7a63 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=mips 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 >>): In file included from include/linux/string.h:253, from include/linux/bitmap.h:10, from include/linux/cpumask.h:12, from arch/mips/include/asm/processor.h:15, from arch/mips/include/asm/thread_info.h:16, from include/linux/thread_info.h:60, from include/linux/uio.h:9, from include/linux/socket.h:8, from include/uapi/linux/can.h:50, from drivers/net/can/flexcan.c:14: In function '__fortify_memset', inlined from 'flexcan_ram_init' at arch/mips/include/asm/io.h:495:2, inlined from 'flexcan_chip_start' at drivers/net/can/flexcan.c:1485:3: 194 | __write_overflow_field(); | ^~~~~~~~~~~~~~~~~~~~~~~~ In function '__fortify_memset', inlined from 'flexcan_ram_init' at arch/mips/include/asm/io.h:495:2, inlined from 'flexcan_chip_start' at drivers/net/can/flexcan.c:1485:3: 194 | __write_overflow_field(); | ^~~~~~~~~~~~~~~~~~~~~~~~ vim +/__write_overflow_field +194 include/linux/fortify-string.h 178 179 #define memset(p, c, s) __fortify_memset(p, c, s) 180 __FORTIFY_INLINE void *__fortify_memset(void *p, int c, __kernel_size_t size) 181 { 182 size_t p_size = __builtin_object_size(p, 0); 183 size_t p_size_field = __builtin_object_size(p, 1); 184 185 if (__builtin_constant_p(size)) { 186 /* 187 * Length argument is a constant expression, so we 188 * can perform compile-time bounds checking where 189 * buffer sizes are known. 190 */ 191 192 /* Disallow size argument larger than dest field. */ 193 if (p_size_field < size) 195 } else { 196 /* 197 * Length argument is not a constant expression, so 198 * run-time bounds checking can happen where buffer 199 * sizes are known. 200 */ 201 202 /* 203 * Warn when writing beyond destination field size. 204 * Since flexible-arrays are considered 0 bytes, we 205 * must ignore 0 sizes at runtime for now. 206 */ 207 if (p_size_field && p_size != p_size_field && p_size_field < size) 208 fortify_warn_write("memset", p_size_field, size); 209 210 /* 211 * Always stop accesses beyond the struct that contains the 212 * field, when the buffer's remaining size is known. 213 */ 214 if (p_size != (size_t)(-1) && p_size < size) 215 fortify_panic("memset"); 216 } 217 return __underlying_memset(p, c, size); 218 } 219 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org