[kbuild-all] [linux-next:master 1562/1734] include/linux/fortify-string.h:275:25: 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/next/linux-next.git master head: d25ee88530253138d0b20d43511ca5acbda4e9f7 commit: 602670289b69b2fded3a0b2240c4877e3a015ac6 [1562/1734] fortify: Detect struct member overflows in memcpy() at compile-time config: arm-aspeed_g5_defconfig (https://download.01.org/0day-ci/archive/20220125/202201251833.Hon4gcuF-lk...) compiler: arm-linux-gnueabi-gcc (GCC) 11.2.0 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/next/linux-next.git/commi... git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git git fetch --no-tags linux-next master git checkout 602670289b69b2fded3a0b2240c4877e3a015ac6 # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=arm SHELL=/bin/bash net/core/ 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:11, from include/linux/cpumask.h:12, from include/linux/smp.h:13, from include/linux/lockdep.h:14, from include/linux/spinlock.h:62, from include/linux/wait.h:9, from include/linux/wait_bit.h:8, from include/linux/fs.h:6, from include/linux/highmem.h:5, from include/linux/bvec.h:10, from include/linux/skbuff.h:17, from net/core/flow_dissector.c:3: In function 'fortify_memcpy_chk', inlined from '__skb_flow_dissect' at net/core/flow_dissector.c:1034:3: 275 | __read_overflow2_field(q_size_field, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ vim +/__read_overflow2_field +275 include/linux/fortify-string.h 213 214 /* 215 * To make sure the compiler can enforce protection against buffer overflows, 216 * memcpy(), memmove(), and memset() must not be used beyond individual 217 * struct members. If you need to copy across multiple members, please use 218 * struct_group() to create a named mirror of an anonymous struct union. 219 * (e.g. see struct sk_buff.) 220 * 221 * Mitigation coverage 222 * Bounds checking at: 223 * +-------+-------+-------+-------+ 224 * | Compile time | Run time | 225 * memcpy() argument sizes: | write | read | write | read | 226 * +-------+-------+-------+-------+ 227 * memcpy(known, known, constant) | y | y | n/a | n/a | 228 * memcpy(unknown, known, constant) | n | y | V | n/a | 229 * memcpy(known, unknown, constant) | y | n | n/a | V | 230 * memcpy(unknown, unknown, constant) | n | n | V | V | 231 * memcpy(known, known, dynamic) | n | n | b | B | 232 * memcpy(unknown, known, dynamic) | n | n | V | B | 233 * memcpy(known, unknown, dynamic) | n | n | b | V | 234 * memcpy(unknown, unknown, dynamic) | n | n | V | V | 235 * +-------+-------+-------+-------+ 236 * 237 * y = deterministic compile-time bounds checking 238 * n = cannot do deterministic compile-time bounds checking 239 * n/a = no run-time bounds checking needed since compile-time deterministic 240 * b = perform run-time bounds checking 241 * B = can perform run-time bounds checking, but current unenforced 242 * V = vulnerable to run-time overflow 243 * 244 */ 245 __FORTIFY_INLINE void fortify_memcpy_chk(__kernel_size_t size, 246 const size_t p_size, 247 const size_t q_size, 248 const size_t p_size_field, 249 const size_t q_size_field, 250 const char *func) 251 { 252 if (__builtin_constant_p(size)) { 253 /* 254 * Length argument is a constant expression, so we 255 * can perform compile-time bounds checking where 256 * buffer sizes are known. 257 */ 258 259 /* Error when size is larger than enclosing struct. */ 260 if (p_size > p_size_field && p_size < size) 261 __write_overflow(); 262 if (q_size > q_size_field && q_size < size) 263 __read_overflow2(); 264 265 /* Warn when write size argument larger than dest field. */ 266 if (p_size_field < size) 267 __write_overflow_field(p_size_field, size); 268 /* 269 * Warn for source field over-read when building with W=1 270 * or when an over-write happened, so both can be fixed at 271 * the same time. 272 */ 273 if ((IS_ENABLED(KBUILD_EXTRA_WARN1) || p_size_field < size) && 274 q_size_field < size) 276 } 277 /* 278 * At this point, length argument may not be a constant expression, 279 * so run-time bounds checking can be done where buffer sizes are 280 * known. (This is not an "else" because the above checks may only 281 * be compile-time warnings, and we want to still warn for run-time 282 * overflows.) 283 */ 284 285 /* 286 * Always stop accesses beyond the struct that contains the 287 * field, when the buffer's remaining size is known. 288 * (The -1 test is to optimize away checks where the buffer 289 * lengths are unknown.) 290 */ 291 if ((p_size != (size_t)(-1) && p_size < size) || 292 (q_size != (size_t)(-1) && q_size < size)) 293 fortify_panic(func); 294 } 295 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org