[zanussi-trace:ftrace/misc-bugfixes-v1 6/7] include/linux/fortify-string.h:47:30: warning: '__builtin_strncat' output truncated before terminating nul copying as many bytes from a string as its length

[kernel test robot <lkp@intel.com>]

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/zanussi/linux-trace.git ftrace/misc-bugfixes-v1
head:   a291c672d6e1d7f557d9e15a5ac3f0b446e29dcd
commit: b519e15e681319e99055a92c8d090072ebb2b179 [6/7] tracing: Remove size restriction on hist trigger cmd error logging
config: i386-randconfig-a002-20220124 (https://download.01.org/0day-ci/archive/20220128/202201281016.u1LRBCEw-lkp(a)intel.com/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/zanussi/linux-trace.git/commit/?id=b519e15e681319e99055a92c8d090072ebb2b179
        git remote add zanussi-trace https://git.kernel.org/pub/scm/linux/kernel/git/zanussi/linux-trace.git
        git fetch --no-tags zanussi-trace ftrace/misc-bugfixes-v1
        git checkout b519e15e681319e99055a92c8d090072ebb2b179
        # save the config file to linux build tree
        mkdir build_dir
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash kernel/trace/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

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/stat.h:19,
                    from include/linux/module.h:13,
                    from kernel/trace/trace_events_hist.c:8:
   In function 'strncat',
       inlined from 'last_cmd_set' at kernel/trace/trace_events_hist.c:759:2,
       inlined from 'event_hist_trigger_parse' at kernel/trace/trace_events_hist.c:6190:3:
>> include/linux/fortify-string.h:47:30: warning: '__builtin_strncat' output truncated before terminating nul copying as many bytes from a string as its length [-Wstringop-truncation]
      47 | #define __underlying_strncat __builtin_strncat
         |                              ^
   include/linux/fortify-string.h:191:10: note: in expansion of macro '__underlying_strncat'
     191 |   return __underlying_strncat(p, q, count);
         |          ^~~~~~~~~~~~~~~~~~~~
   kernel/trace/trace_events_hist.c: In function 'event_hist_trigger_parse':
   include/linux/fortify-string.h:46:29: note: length computed here
      46 | #define __underlying_strlen __builtin_strlen
         |                             ^
   include/linux/fortify-string.h:102:10: note: in expansion of macro '__underlying_strlen'
     102 |   return __underlying_strlen(p);
         |          ^~~~~~~~~~~~~~~~~~~


vim +/__builtin_strncat +47 include/linux/fortify-string.h

3009f891bb9f328 Kees Cook      2021-08-02  26  
a28a6e860c6cf23 Francis Laniel 2021-02-25  27  #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
a28a6e860c6cf23 Francis Laniel 2021-02-25  28  extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
a28a6e860c6cf23 Francis Laniel 2021-02-25  29  extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
a28a6e860c6cf23 Francis Laniel 2021-02-25  30  extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
a28a6e860c6cf23 Francis Laniel 2021-02-25  31  extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
a28a6e860c6cf23 Francis Laniel 2021-02-25  32  extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
a28a6e860c6cf23 Francis Laniel 2021-02-25  33  extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
a28a6e860c6cf23 Francis Laniel 2021-02-25  34  extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
a28a6e860c6cf23 Francis Laniel 2021-02-25  35  extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
a28a6e860c6cf23 Francis Laniel 2021-02-25  36  extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
a28a6e860c6cf23 Francis Laniel 2021-02-25  37  extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
a28a6e860c6cf23 Francis Laniel 2021-02-25  38  #else
a28a6e860c6cf23 Francis Laniel 2021-02-25  39  #define __underlying_memchr	__builtin_memchr
a28a6e860c6cf23 Francis Laniel 2021-02-25  40  #define __underlying_memcmp	__builtin_memcmp
a28a6e860c6cf23 Francis Laniel 2021-02-25  41  #define __underlying_memcpy	__builtin_memcpy
a28a6e860c6cf23 Francis Laniel 2021-02-25  42  #define __underlying_memmove	__builtin_memmove
a28a6e860c6cf23 Francis Laniel 2021-02-25  43  #define __underlying_memset	__builtin_memset
a28a6e860c6cf23 Francis Laniel 2021-02-25  44  #define __underlying_strcat	__builtin_strcat
a28a6e860c6cf23 Francis Laniel 2021-02-25  45  #define __underlying_strcpy	__builtin_strcpy
a28a6e860c6cf23 Francis Laniel 2021-02-25  46  #define __underlying_strlen	__builtin_strlen
a28a6e860c6cf23 Francis Laniel 2021-02-25 @47  #define __underlying_strncat	__builtin_strncat
a28a6e860c6cf23 Francis Laniel 2021-02-25  48  #define __underlying_strncpy	__builtin_strncpy
a28a6e860c6cf23 Francis Laniel 2021-02-25  49  #endif
a28a6e860c6cf23 Francis Laniel 2021-02-25  50  

:::::: The code at line 47 was first introduced by commit
:::::: a28a6e860c6cf231cf3c5171c75c342adcd00406 string.h: move fortified functions definitions in a dedicated header.

:::::: TO: Francis Laniel <laniel_francis@privacyrequired.com>
:::::: CC: Linus Torvalds <torvalds@linux-foundation.org>

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org