tree: https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git kspp/memcpy/next-20210618/v0 head: fd2aa2a169de8bde9502e7a2fc48cd03d4bfd996 commit: 21405e341f4b8742f8c6d8b91ad39348d7cf970f [58/82] fortify: Detect struct member overflows in memcpy() config: i386-randconfig-r026-20210618 (attached as .config) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce (this is a W=1 build): # 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 git checkout 21405e341f4b8742f8c6d8b91ad39348d7cf970f # save the attached .config to linux build tree make W=1 ARCH=i386 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 arch/x86/include/asm/page_32.h:35, from arch/x86/include/asm/page.h:14, from arch/x86/include/asm/thread_info.h:12, from include/linux/thread_info.h:60, from arch/x86/include/asm/preempt.h:7, from include/linux/preempt.h:78, from include/linux/spinlock.h:51, from include/linux/wait.h:9, from include/linux/wait_bit.h:8, from include/linux/fs.h:6, from fs/cifs/smb2pdu.c:31: In function '__fortify_memcpy_chk', inlined from '__fortify_memcpy' at include/linux/fortify-string.h:277:2, inlined from 'SMB2_open' at fs/cifs/smb2pdu.c:2909:3: include/linux/fortify-string.h:246:4: warning: call to '__read_overflow2_field' declared with attribute warning: detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Wattribute-warning] 246 | __read_overflow2_field(); | ^~~~~~~~~~~~~~~~~~~~~~~~ In function '__fortify_memcpy_chk', inlined from '__fortify_memcpy' at include/linux/fortify-string.h:277:2, inlined from '__SMB2_close' at fs/cifs/smb2pdu.c:3262:4: include/linux/fortify-string.h:246:4: warning: call to '__read_overflow2_field' declared with attribute warning: detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Wattribute-warning] 246 | __read_overflow2_field(); | ^~~~~~~~~~~~~~~~~~~~~~~~ In function '__fortify_memcpy_chk', inlined from '__fortify_memcpy' at include/linux/fortify-string.h:277:2, inlined from 'posix_info_parse' at fs/cifs/smb2pdu.c:4555:3: 239 | __write_overflow_field(); | ^~~~~~~~~~~~~~~~~~~~~~~~ In function '__fortify_memcpy_chk', inlined from '__fortify_memcpy' at include/linux/fortify-string.h:277:2, inlined from 'posix_info_parse' at fs/cifs/smb2pdu.c:4557:3: 239 | __write_overflow_field(); | ^~~~~~~~~~~~~~~~~~~~~~~~ vim +/__write_overflow_field +239 include/linux/fortify-string.h 189 190 /* 191 * To make sure the compiler can enforce protection against buffer overflows, 192 * memcpy(), memmove(), and memset() must not be used beyond individual 193 * struct members. If you need to copy across multiple members, please use 194 * struct_group() to create a named mirror of an anonymous struct union. 195 * (e.g. see struct sk_buff.) 196 * 197 * Mitigation coverage 198 * Bounds checking at: 199 * +-------+-------+-------+-------+ 200 * | Compile time | Run time | 201 * memcpy() argument sizes: | write | read | write | read | 202 * +-------+-------+-------+-------+ 203 * memcpy(known, known, constant) | y | y | n/a | n/a | 204 * memcpy(unknown, known, constant) | n | y | V | n/a | 205 * memcpy(known, unknown, constant) | y | n | n/a | V | 206 * memcpy(unknown, unknown, constant) | n | n | V | V | 207 * memcpy(known, known, dynamic) | n | n | b | B | 208 * memcpy(unknown, known, dynamic) | n | n | V | B | 209 * memcpy(known, unknown, dynamic) | n | n | b | V | 210 * memcpy(unknown, unknown, dynamic) | n | n | V | V | 211 * +-------+-------+-------+-------+ 212 * 213 * y = deterministic compile-time bounds checking 214 * n = cannot do deterministic compile-time bounds checking 215 * n/a = no run-time bounds checking needed since compile-time deterministic 216 * b = perform run-time bounds checking 217 * B = can perform run-time bounds checking, but current unenforced 218 * V = vulnerable to run-time overflow 219 * 220 */ 221 __FORTIFY_INLINE void __fortify_memcpy_chk(void *p, const void *q, 222 __kernel_size_t size, 223 const char *func) 224 { 225 size_t p_size = __builtin_object_size(p, 0); 226 size_t q_size = __builtin_object_size(q, 0); 227 size_t p_size_field = __builtin_object_size(p, 1); 228 size_t q_size_field = __builtin_object_size(q, 1); 229 230 if (__builtin_constant_p(size)) { 231 /* 232 * Length argument is a constant expression, so we 233 * can perform compile-time bounds checking where 234 * buffer sizes are known. 235 */ 236 237 /* Warn when write size argument larger than dest field. */ 238 if (p_size_field < size) 240 /* 241 * Warn for over-read under W=1 or when an over-write 242 * happened, so both can be fixed at the same time. 243 */ 244 if ((IS_ENABLED(KBUILD_EXTRA_WARN1) || p_size_field < size) && 245 q_size_field < size) 246 __read_overflow2_field(); 247 } else { 248 /* 249 * Length argument is not a constant expression, so 250 * run-time bounds checking can happen where buffer 251 * sizes are known. 252 */ 253 254 /* Warn when writing beyond destination field size. */ 255 if (p_size != p_size_field && p_size_field < size) 256 fortify_warn_write(func, p_size_field, size); 257 /* Warn when reading beyond source field size. */ 258 /* 259 if (q_size != q_size_field && q_size_field < size) 260 fortify_warn_read(func, q_size_field, size); 261 */ 262 263 /* 264 * Always stop accesses beyond the struct that contains the 265 * field, when the buffer's remaining size is known. 266 */ 267 if ((p_size != (size_t)(-1) && p_size < size) || 268 (q_size != (size_t)(-1) && q_size < size)) 269 fortify_panic(func); 270 } 271 } 272 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org