[kbuild-all] [linux-next:master 3921/8516] include/linux/seq_file.h:247:9: warning: 'strncpy' output may be truncated copying 4 bytes from a string of length 4

tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: 9803fb968c8c2e1283f67b3baeb88e0adba435b4 commit: e37b3dd063a1a68e28a7cfaf77c84c472112e330 [3921/8516] s390: enable KCSAN config: s390-randconfig-r044-20210817 (attached as .config) compiler: s390-linux-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 e37b3dd063a1a68e28a7cfaf77c84c472112e330 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=s390 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/seq_file_net.h:5, from include/net/net_namespace.h:179, from include/linux/inet.h:42, from fs/ocfs2/super.c:21: fs/ocfs2/super.c: In function 'ocfs2_show_options': 247 | strncpy(val_buf, value, length); \ | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ fs/ocfs2/super.c:1539:17: note: in expansion of macro 'seq_show_option_n' 1539 | seq_show_option_n(s, "cluster_stack", osb->osb_cluster_stack, | ^~~~~~~~~~~~~~~~~ vim +/strncpy +247 include/linux/seq_file.h a068acf2ee7769 Kees Cook 2015-09-04 233 a068acf2ee7769 Kees Cook 2015-09-04 234 /** a068acf2ee7769 Kees Cook 2015-09-04 235 * seq_show_option_n - display mount options with appropriate escapes a068acf2ee7769 Kees Cook 2015-09-04 236 * where @value must be a specific length. a068acf2ee7769 Kees Cook 2015-09-04 237 * @m: the seq_file handle a068acf2ee7769 Kees Cook 2015-09-04 238 * @name: the mount option name a068acf2ee7769 Kees Cook 2015-09-04 239 * @value: the mount option name's value, cannot be NULL a068acf2ee7769 Kees Cook 2015-09-04 240 * @length: the length of @value to display a068acf2ee7769 Kees Cook 2015-09-04 241 * a068acf2ee7769 Kees Cook 2015-09-04 242 * This is a macro since this uses "length" to define the size of the a068acf2ee7769 Kees Cook 2015-09-04 243 * stack buffer. a068acf2ee7769 Kees Cook 2015-09-04 244 */ a068acf2ee7769 Kees Cook 2015-09-04 245 #define seq_show_option_n(m, name, value, length) { \ a068acf2ee7769 Kees Cook 2015-09-04 246 char val_buf[length + 1]; \ a068acf2ee7769 Kees Cook 2015-09-04 @247 strncpy(val_buf, value, length); \ a068acf2ee7769 Kees Cook 2015-09-04 248 val_buf[length] = '\0'; \ a068acf2ee7769 Kees Cook 2015-09-04 249 seq_show_option(m, name, val_buf); \ a068acf2ee7769 Kees Cook 2015-09-04 250 } a068acf2ee7769 Kees Cook 2015-09-04 251 :::::: The code at line 247 was first introduced by commit :::::: a068acf2ee77693e0bf39d6e07139ba704f461c3 fs: create and use seq_show_option for escaping :::::: TO: Kees Cook <keescook(a)chromium.org&gt; :::::: CC: Linus Torvalds <torvalds(a)linux-foundation.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org