[kbuild-all] [kees:kspp/memcpy/next-20210621/v0 53/86] 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()?

tree: https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git kspp/memcpy/next-20210621/v0 head: 711a2c0c23d479d212e8d80f5dcaaf267162c8de commit: b14704acbcd3290c2ab263615639d7e2f2a2e501 [53/86] fortify: Detect struct member overflows in memcpy() config: i386-randconfig-r025-20210621 (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-20210621/v0 git checkout b14704acbcd3290c2ab263615639d7e2f2a2e501 # 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/processor.h:19, from arch/x86/include/asm/timex.h:5, from include/linux/timex.h:65, from include/linux/time32.h:13, from include/linux/time.h:60, from include/linux/ktime.h:24, from include/linux/timer.h:6, from include/linux/netdevice.h:24, from net/mac80211/wpa.c:9: In function '__fortify_memcpy_chk', inlined from '__fortify_memcpy' at include/linux/fortify-string.h:281:2, inlined from 'bip_aad.isra.0' at net/mac80211/wpa.c:912:2: 246 | __read_overflow2_field(); | ^~~~~~~~~~~~~~~~~~~~~~~~ In function '__fortify_memcpy_chk', inlined from '__fortify_memcpy' at include/linux/fortify-string.h:281:2, inlined from 'ccmp_special_blocks.isra.0' at net/mac80211/wpa.c:365:2: 246 | __read_overflow2_field(); | ^~~~~~~~~~~~~~~~~~~~~~~~ In function '__fortify_memcpy_chk', inlined from '__fortify_memcpy' at include/linux/fortify-string.h:281:2, inlined from 'gcmp_special_blocks.isra.0' at net/mac80211/wpa.c:597:2: 246 | __read_overflow2_field(); | ^~~~~~~~~~~~~~~~~~~~~~~~ vim +/__read_overflow2_field +246 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) 239 __write_overflow_field(); 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) 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 /* 255 * Warn when writing beyond destination field size. 256 * Since flexible-arrays are considered 0 bytes, we 257 * must ignore 0 sizes at runtime for now. 258 */ 259 if (p_size_field && p_size != p_size_field && p_size_field < size) 260 fortify_warn_write(func, p_size_field, size); 261 /* Warn when reading beyond source field size. */ 262 /* 263 if (q_size_field && q_size != q_size_field && q_size_field < size) 264 fortify_warn_read(func, q_size_field, size); 265 */ 266 267 /* 268 * Always stop accesses beyond the struct that contains the 269 * field, when the buffer's remaining size is known. 270 */ 271 if ((p_size != (size_t)(-1) && p_size < size) || 272 (q_size != (size_t)(-1) && q_size < size)) 273 fortify_panic(func); 274 } 275 } 276 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org