[kbuild-all] [kees:memcpy/step2/next-20211206 19/19] include/linux/fortify-string.h:324:4: warning: call to __read_overflow2_field declared with 'warning' attribute: 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 memcpy/step2/next-20211206 head: 082faead4a3c2e5d9f541f97d8d4d5fa0f88dce0 commit: 082faead4a3c2e5d9f541f97d8d4d5fa0f88dce0 [19/19] fortify: Work around Clang inlining bugs config: i386-randconfig-a013-20211207 (https://download.01.org/0day-ci/archive/20211208/202112080732.rL3hdjwC-lk...) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 097a1cb1d5ebb3a0ec4bcaed8ba3ff6a8e33c00a) 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 memcpy/step2/next-20211206 git checkout 082faead4a3c2e5d9f541f97d8d4d5fa0f88dce0 # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash kernel/entry/ 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 kernel/entry/common.c:3: In file included from include/linux/context_tracking.h:5: In file included from include/linux/sched.h:14: In file included from include/linux/pid.h:5: In file included from include/linux/rculist.h:11: In file included from include/linux/rcupdate.h:27: In file included from include/linux/preempt.h:78: In file included from arch/x86/include/asm/preempt.h:7: In file included from include/linux/thread_info.h:60: In file included from arch/x86/include/asm/thread_info.h:12: In file included from arch/x86/include/asm/page.h:14: In file included from arch/x86/include/asm/page_32.h:35: In file included from include/linux/string.h:253: __read_overflow2_field(q_size_field, size); ^ 2 warnings generated. vim +/warning +324 include/linux/fortify-string.h 2fc46de99fed34 Kees Cook 2021-06-16 255 2fc46de99fed34 Kees Cook 2021-06-16 256 /* 2fc46de99fed34 Kees Cook 2021-06-16 257 * __builtin_object_size() must be captured here to avoid evaluating argument 2fc46de99fed34 Kees Cook 2021-06-16 258 * side-effects further into the macro layers. 2fc46de99fed34 Kees Cook 2021-06-16 259 */ 2fc46de99fed34 Kees Cook 2021-06-16 260 #define memset(p, c, s) __fortify_memset_chk(p, c, s, \ 2fc46de99fed34 Kees Cook 2021-06-16 261 __builtin_object_size(p, 0), __builtin_object_size(p, 1)) a28a6e860c6cf2 Francis Laniel 2021-02-25 262 a91965903a44bf Kees Cook 2021-04-20 263 /* a91965903a44bf Kees Cook 2021-04-20 264 * To make sure the compiler can enforce protection against buffer overflows, a91965903a44bf Kees Cook 2021-04-20 265 * memcpy(), memmove(), and memset() must not be used beyond individual a91965903a44bf Kees Cook 2021-04-20 266 * struct members. If you need to copy across multiple members, please use a91965903a44bf Kees Cook 2021-04-20 267 * struct_group() to create a named mirror of an anonymous struct union. a91965903a44bf Kees Cook 2021-04-20 268 * (e.g. see struct sk_buff.) a91965903a44bf Kees Cook 2021-04-20 269 * a91965903a44bf Kees Cook 2021-04-20 270 * Mitigation coverage a91965903a44bf Kees Cook 2021-04-20 271 * Bounds checking at: a91965903a44bf Kees Cook 2021-04-20 272 * +-------+-------+-------+-------+ a91965903a44bf Kees Cook 2021-04-20 273 * | Compile time | Run time | a91965903a44bf Kees Cook 2021-04-20 274 * memcpy() argument sizes: | write | read | write | read | a91965903a44bf Kees Cook 2021-04-20 275 * +-------+-------+-------+-------+ a91965903a44bf Kees Cook 2021-04-20 276 * memcpy(known, known, constant) | y | y | n/a | n/a | a91965903a44bf Kees Cook 2021-04-20 277 * memcpy(unknown, known, constant) | n | y | V | n/a | a91965903a44bf Kees Cook 2021-04-20 278 * memcpy(known, unknown, constant) | y | n | n/a | V | a91965903a44bf Kees Cook 2021-04-20 279 * memcpy(unknown, unknown, constant) | n | n | V | V | a91965903a44bf Kees Cook 2021-04-20 280 * memcpy(known, known, dynamic) | n | n | b | B | a91965903a44bf Kees Cook 2021-04-20 281 * memcpy(unknown, known, dynamic) | n | n | V | B | a91965903a44bf Kees Cook 2021-04-20 282 * memcpy(known, unknown, dynamic) | n | n | b | V | a91965903a44bf Kees Cook 2021-04-20 283 * memcpy(unknown, unknown, dynamic) | n | n | V | V | a91965903a44bf Kees Cook 2021-04-20 284 * +-------+-------+-------+-------+ a91965903a44bf Kees Cook 2021-04-20 285 * a91965903a44bf Kees Cook 2021-04-20 286 * y = deterministic compile-time bounds checking a91965903a44bf Kees Cook 2021-04-20 287 * n = cannot do deterministic compile-time bounds checking a91965903a44bf Kees Cook 2021-04-20 288 * n/a = no run-time bounds checking needed since compile-time deterministic a91965903a44bf Kees Cook 2021-04-20 289 * b = perform run-time bounds checking a91965903a44bf Kees Cook 2021-04-20 290 * B = can perform run-time bounds checking, but current unenforced a91965903a44bf Kees Cook 2021-04-20 291 * V = vulnerable to run-time overflow a91965903a44bf Kees Cook 2021-04-20 292 * a91965903a44bf Kees Cook 2021-04-20 293 */ a91965903a44bf Kees Cook 2021-04-20 294 __FORTIFY_INLINE void fortify_memcpy_chk(__kernel_size_t size, a91965903a44bf Kees Cook 2021-04-20 295 const size_t p_size, a91965903a44bf Kees Cook 2021-04-20 296 const size_t q_size, a91965903a44bf Kees Cook 2021-04-20 297 const size_t p_size_field, a91965903a44bf Kees Cook 2021-04-20 298 const size_t q_size_field, a91965903a44bf Kees Cook 2021-04-20 299 const char *func) a28a6e860c6cf2 Francis Laniel 2021-02-25 300 { a28a6e860c6cf2 Francis Laniel 2021-02-25 301 if (__builtin_constant_p(size)) { a91965903a44bf Kees Cook 2021-04-20 302 /* a91965903a44bf Kees Cook 2021-04-20 303 * Length argument is a constant expression, so we a91965903a44bf Kees Cook 2021-04-20 304 * can perform compile-time bounds checking where a91965903a44bf Kees Cook 2021-04-20 305 * buffer sizes are known. a91965903a44bf Kees Cook 2021-04-20 306 */ a91965903a44bf Kees Cook 2021-04-20 307 a91965903a44bf Kees Cook 2021-04-20 308 /* Error when size is larger than enclosing struct. */ a91965903a44bf Kees Cook 2021-04-20 309 if (p_size > p_size_field && p_size < size) a28a6e860c6cf2 Francis Laniel 2021-02-25 310 __write_overflow(); a91965903a44bf Kees Cook 2021-04-20 311 if (q_size > q_size_field && q_size < size) a28a6e860c6cf2 Francis Laniel 2021-02-25 312 __read_overflow2(); a91965903a44bf Kees Cook 2021-04-20 313 a91965903a44bf Kees Cook 2021-04-20 314 /* Warn when write size argument larger than dest field. */ a91965903a44bf Kees Cook 2021-04-20 315 if (p_size_field < size) a91965903a44bf Kees Cook 2021-04-20 316 __write_overflow_field(p_size_field, size); a91965903a44bf Kees Cook 2021-04-20 317 /* a91965903a44bf Kees Cook 2021-04-20 318 * Warn for source field over-read when building with W=1 a91965903a44bf Kees Cook 2021-04-20 319 * or when an over-write happened, so both can be fixed at a91965903a44bf Kees Cook 2021-04-20 320 * the same time. a91965903a44bf Kees Cook 2021-04-20 321 */ a91965903a44bf Kees Cook 2021-04-20 322 if ((IS_ENABLED(KBUILD_EXTRA_WARN1) || p_size_field < size) && a91965903a44bf Kees Cook 2021-04-20 323 q_size_field < size) a91965903a44bf Kees Cook 2021-04-20 @324 __read_overflow2_field(q_size_field, size); a28a6e860c6cf2 Francis Laniel 2021-02-25 325 } a91965903a44bf Kees Cook 2021-04-20 326 /* a91965903a44bf Kees Cook 2021-04-20 327 * At this point, length argument may not be a constant expression, a91965903a44bf Kees Cook 2021-04-20 328 * so run-time bounds checking can be done where buffer sizes are a91965903a44bf Kees Cook 2021-04-20 329 * known. (This is not an "else" because the above checks may only a91965903a44bf Kees Cook 2021-04-20 330 * be compile-time warnings, and we want to still warn for run-time a91965903a44bf Kees Cook 2021-04-20 331 * overflows.) a91965903a44bf Kees Cook 2021-04-20 332 */ a91965903a44bf Kees Cook 2021-04-20 333 a91965903a44bf Kees Cook 2021-04-20 334 /* a91965903a44bf Kees Cook 2021-04-20 335 * Always stop accesses beyond the struct that contains the a91965903a44bf Kees Cook 2021-04-20 336 * field, when the buffer's remaining size is known. a91965903a44bf Kees Cook 2021-04-20 337 * (The -1 test is to optimize away checks where the buffer a91965903a44bf Kees Cook 2021-04-20 338 * lengths are unknown.) a91965903a44bf Kees Cook 2021-04-20 339 */ a91965903a44bf Kees Cook 2021-04-20 340 if ((p_size != (size_t)(-1) && p_size < size) || a91965903a44bf Kees Cook 2021-04-20 341 (q_size != (size_t)(-1) && q_size < size)) a91965903a44bf Kees Cook 2021-04-20 342 fortify_panic(func); a28a6e860c6cf2 Francis Laniel 2021-02-25 343 } a28a6e860c6cf2 Francis Laniel 2021-02-25 344 :::::: The code at line 324 was first introduced by commit :::::: a91965903a44bf236856efc7e20c6334c4e07388 fortify: Detect struct member overflows in memcpy() at compile-time :::::: TO: Kees Cook <keescook(a)chromium.org&gt; :::::: CC: Kees Cook <keescook(a)chromium.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org