Hi Michal, Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on linus/master] [also build test WARNING on v4.18-rc1 next-20180619] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Michal-Kubecek/proc-add-missing-0-back-to-proc-pid-cmdline/20180619-210800 config: x86_64-randconfig-x015-201824 (attached as .config) compiler: gcc-7 (Debian 7.3.0-16) 7.3.0 reproduce: # save the attached .config to linux build tree make ARCH=x86_64 Note: it may well be a FALSE warning. FWIW you are at least aware of it now. http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings All warnings (new ones prefixed by >>): fs/proc/base.c: In function 'proc_pid_cmdline_read': >> fs/proc/base.c:248:9: warning: 'pos' may be used uninitialized in this >> function [-Wmaybe-uninitialized] count = env_end - pos; ~~~~~~^~~~~~~~~~~~~~~ fs/proc/base.c:212:25: note: 'pos' was declared here unsigned long req_pos, pos, len; ^~~ vim +/pos +248 fs/proc/base.c ^1da177e Linus Torvalds 2005-04-16 207 e4b4e441 Linus Torvalds 2018-05-17 208 static ssize_t get_mm_cmdline(struct mm_struct *mm, char __user *buf, 5ab82718 Linus Torvalds 2018-05-17 209 size_t count, loff_t *ppos) ^1da177e Linus Torvalds 2005-04-16 210 { c2c0bb44 Alexey Dobriyan 2015-06-25 211 unsigned long arg_start, arg_end, env_start, env_end; bf62f801 Michal Kubecek 2018-06-19 212 unsigned long req_pos, pos, len; bf62f801 Michal Kubecek 2018-06-19 213 bool end_found = false; 5ab82718 Linus Torvalds 2018-05-17 214 char *page; c2c0bb44 Alexey Dobriyan 2015-06-25 215 c2c0bb44 Alexey Dobriyan 2015-06-25 216 /* Check if process spawned far enough to have cmdline. */ e4b4e441 Linus Torvalds 2018-05-17 217 if (!mm->env_end) e4b4e441 Linus Torvalds 2018-05-17 218 return 0; c2c0bb44 Alexey Dobriyan 2015-06-25 219 88aa7cc6 Yang Shi 2018-06-07 220 spin_lock(&mm->arg_lock); c2c0bb44 Alexey Dobriyan 2015-06-25 221 arg_start = mm->arg_start; c2c0bb44 Alexey Dobriyan 2015-06-25 222 arg_end = mm->arg_end; c2c0bb44 Alexey Dobriyan 2015-06-25 223 env_start = mm->env_start; c2c0bb44 Alexey Dobriyan 2015-06-25 224 env_end = mm->env_end; 88aa7cc6 Yang Shi 2018-06-07 225 spin_unlock(&mm->arg_lock); c2c0bb44 Alexey Dobriyan 2015-06-25 226 5ab82718 Linus Torvalds 2018-05-17 227 if (arg_start >= arg_end) 5ab82718 Linus Torvalds 2018-05-17 228 return 0; 6a6cbe75 Alexey Dobriyan 2018-06-07 229 2ca66ff7 Alexey Dobriyan 2014-08-08 230 /* 5ab82718 Linus Torvalds 2018-05-17 231 * We have traditionally allowed the user to re-write 5ab82718 Linus Torvalds 2018-05-17 232 * the argument strings and overflow the end result 5ab82718 Linus Torvalds 2018-05-17 233 * into the environment section. But only do that if 5ab82718 Linus Torvalds 2018-05-17 234 * the environment area is contiguous to the arguments. 2ca66ff7 Alexey Dobriyan 2014-08-08 235 */ 5ab82718 Linus Torvalds 2018-05-17 236 if (env_start != arg_end || env_start >= env_end) 5ab82718 Linus Torvalds 2018-05-17 237 env_start = env_end = arg_end; 3cb4e162 Alexey Dobriyan 2018-06-07 238 5ab82718 Linus Torvalds 2018-05-17 239 /* We're not going to care if "*ppos" has high bits set */ bf62f801 Michal Kubecek 2018-06-19 240 req_pos = arg_start + *ppos; c2c0bb44 Alexey Dobriyan 2015-06-25 241 5ab82718 Linus Torvalds 2018-05-17 242 /* .. but we do check the result is in the proper range */ bf62f801 Michal Kubecek 2018-06-19 243 if (req_pos < arg_start || req_pos >= env_end) 5ab82718 Linus Torvalds 2018-05-17 244 return 0; 3cb4e162 Alexey Dobriyan 2018-06-07 245 5ab82718 Linus Torvalds 2018-05-17 246 /* .. and we never go past env_end */ bf62f801 Michal Kubecek 2018-06-19 247 if (env_end - req_pos < count) 5ab82718 Linus Torvalds 2018-05-17 @248 count = env_end - pos; c2c0bb44 Alexey Dobriyan 2015-06-25 249 bf62f801 Michal Kubecek 2018-06-19 250 pos = min_t(unsigned long, req_pos, arg_end - 1); 5ab82718 Linus Torvalds 2018-05-17 251 page = (char *)__get_free_page(GFP_KERNEL); 5ab82718 Linus Torvalds 2018-05-17 252 if (!page) 5ab82718 Linus Torvalds 2018-05-17 253 return -ENOMEM; 5ab82718 Linus Torvalds 2018-05-17 254 5ab82718 Linus Torvalds 2018-05-17 255 len = 0; bf62f801 Michal Kubecek 2018-06-19 256 while (count && !end_found) { 5ab82718 Linus Torvalds 2018-05-17 257 int got; bf62f801 Michal Kubecek 2018-06-19 258 size_t size = count + (pos < req_pos ? req_pos - pos : 0); 5ab82718 Linus Torvalds 2018-05-17 259 bf62f801 Michal Kubecek 2018-06-19 260 size = min_t(size_t, PAGE_SIZE, size); 5ab82718 Linus Torvalds 2018-05-17 261 got = access_remote_vm(mm, pos, page, size, FOLL_ANON); 5ab82718 Linus Torvalds 2018-05-17 262 if (got <= 0) 5ab82718 Linus Torvalds 2018-05-17 263 break; 5ab82718 Linus Torvalds 2018-05-17 264 5ab82718 Linus Torvalds 2018-05-17 265 /* Don't walk past a NUL character once you hit arg_end */ 5ab82718 Linus Torvalds 2018-05-17 266 if (pos + got >= arg_end) { 5ab82718 Linus Torvalds 2018-05-17 267 int n = 0; c2c0bb44 Alexey Dobriyan 2015-06-25 268 c2c0bb44 Alexey Dobriyan 2015-06-25 269 /* 5ab82718 Linus Torvalds 2018-05-17 270 * If we started before 'arg_end' but ended up 5ab82718 Linus Torvalds 2018-05-17 271 * at or after it, we start the NUL character 5ab82718 Linus Torvalds 2018-05-17 272 * check at arg_end-1 (where we expect the normal 5ab82718 Linus Torvalds 2018-05-17 273 * EOF to be). 5ab82718 Linus Torvalds 2018-05-17 274 * 5ab82718 Linus Torvalds 2018-05-17 275 * NOTE! This is smaller than 'got', because 5ab82718 Linus Torvalds 2018-05-17 276 * pos + got >= arg_end c2c0bb44 Alexey Dobriyan 2015-06-25 277 */ 5ab82718 Linus Torvalds 2018-05-17 278 if (pos < arg_end) 5ab82718 Linus Torvalds 2018-05-17 279 n = arg_end - pos - 1; c2c0bb44 Alexey Dobriyan 2015-06-25 280 5ab82718 Linus Torvalds 2018-05-17 281 /* Cut off at first NUL after 'n' */ bf62f801 Michal Kubecek 2018-06-19 282 n += strnlen(page+n, got-n); bf62f801 Michal Kubecek 2018-06-19 283 got = min_t(int, got, n + 1); bf62f801 Michal Kubecek 2018-06-19 284 end_found = !page[n]; 5ab82718 Linus Torvalds 2018-05-17 285 if (!got) 5ab82718 Linus Torvalds 2018-05-17 286 break; c2c0bb44 Alexey Dobriyan 2015-06-25 287 } c2c0bb44 Alexey Dobriyan 2015-06-25 288 bf62f801 Michal Kubecek 2018-06-19 289 if (pos + got <= req_pos) { bf62f801 Michal Kubecek 2018-06-19 290 /* got > 0 here so that pos always advances */ bf62f801 Michal Kubecek 2018-06-19 291 pos += got; bf62f801 Michal Kubecek 2018-06-19 292 continue; bf62f801 Michal Kubecek 2018-06-19 293 } bf62f801 Michal Kubecek 2018-06-19 294 bf62f801 Michal Kubecek 2018-06-19 295 if (pos < req_pos) { bf62f801 Michal Kubecek 2018-06-19 296 got -= (req_pos - pos); bf62f801 Michal Kubecek 2018-06-19 297 pos = req_pos; bf62f801 Michal Kubecek 2018-06-19 298 } 5ab82718 Linus Torvalds 2018-05-17 299 got -= copy_to_user(buf, page, got); 5ab82718 Linus Torvalds 2018-05-17 300 if (unlikely(!got)) { 5ab82718 Linus Torvalds 2018-05-17 301 if (!len) 5ab82718 Linus Torvalds 2018-05-17 302 len = -EFAULT; 5ab82718 Linus Torvalds 2018-05-17 303 break; c2c0bb44 Alexey Dobriyan 2015-06-25 304 } 5ab82718 Linus Torvalds 2018-05-17 305 pos += got; 5ab82718 Linus Torvalds 2018-05-17 306 buf += got; 5ab82718 Linus Torvalds 2018-05-17 307 len += got; 5ab82718 Linus Torvalds 2018-05-17 308 count -= got; c2c0bb44 Alexey Dobriyan 2015-06-25 309 } c2c0bb44 Alexey Dobriyan 2015-06-25 310 c2c0bb44 Alexey Dobriyan 2015-06-25 311 free_page((unsigned long)page); 5ab82718 Linus Torvalds 2018-05-17 312 return len; c2c0bb44 Alexey Dobriyan 2015-06-25 313 } c2c0bb44 Alexey Dobriyan 2015-06-25 314 :::::: The code at line 248 was first introduced by commit :::::: 5ab8271899658042fabc5ae7e6a99066a210bc0e fs/proc: simplify and clarify get_mm_cmdline() function :::::: TO: Linus Torvalds <torva...@linux-foundation.org> :::::: CC: Linus Torvalds <torva...@linux-foundation.org> --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
.config.gz
Description: application/gzip
