[ammarfaizi2-block:rostedt/linux-trace/ftrace/core 13/13] include/linux/fortify-string.h:48:30: warning: '__builtin_strncpy' output truncated before terminating nul copying as many bytes from a string as its length

[kernel test robot]

tree:   https://github.com/ammarfaizi2/linux-block rostedt/linux-trace/ftrace/core
head:   f125ef075cd648a7794aa0cc61a188b1c40c8f94
commit: f125ef075cd648a7794aa0cc61a188b1c40c8f94 [13/13] tracing: Remove size restriction on synthetic event cmd error logging
config: x86_64-randconfig-a011 (https://download.01.org/0day-ci/archive/20220128/202201281716.fJjEsoAS-lkp@xxxxxxxxx/config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/ammarfaizi2/linux-block/commit/f125ef075cd648a7794aa0cc61a188b1c40c8f94
        git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block
        git fetch --no-tags ammarfaizi2-block rostedt/linux-trace/ftrace/core
        git checkout f125ef075cd648a7794aa0cc61a188b1c40c8f94
        # save the config file to linux build tree
        mkdir build_dir
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash kernel/trace/

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

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 arch/x86/include/asm/cpumask.h:5,
                    from arch/x86/include/asm/msr.h:11,
                    from arch/x86/include/asm/processor.h:22,
                    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_synth.c:8:
   In function 'strncpy',
       inlined from 'last_cmd_set.part.0' at kernel/trace/trace_events_synth.c:65:2:
>> include/linux/fortify-string.h:48:30: warning: '__builtin_strncpy' output truncated before terminating nul copying as many bytes from a string as its length [-Wstringop-truncation]
      48 | #define __underlying_strncpy __builtin_strncpy
         |                              ^
   include/linux/fortify-string.h:59:9: note: in expansion of macro '__underlying_strncpy'
      59 |  return __underlying_strncpy(p, q, size);
         |         ^~~~~~~~~~~~~~~~~~~~
   kernel/trace/trace_events_synth.c: In function 'last_cmd_set.part.0':
   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_strncpy +48 include/linux/fortify-string.h

3009f891bb9f32 Kees Cook      2021-08-02  26  
a28a6e860c6cf2 Francis Laniel 2021-02-25  27  #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
a28a6e860c6cf2 Francis Laniel 2021-02-25  28  extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
a28a6e860c6cf2 Francis Laniel 2021-02-25  29  extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
a28a6e860c6cf2 Francis Laniel 2021-02-25  30  extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
a28a6e860c6cf2 Francis Laniel 2021-02-25  31  extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
a28a6e860c6cf2 Francis Laniel 2021-02-25  32  extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
a28a6e860c6cf2 Francis Laniel 2021-02-25  33  extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
a28a6e860c6cf2 Francis Laniel 2021-02-25  34  extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
a28a6e860c6cf2 Francis Laniel 2021-02-25  35  extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
a28a6e860c6cf2 Francis Laniel 2021-02-25  36  extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
a28a6e860c6cf2 Francis Laniel 2021-02-25  37  extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
a28a6e860c6cf2 Francis Laniel 2021-02-25  38  #else
a28a6e860c6cf2 Francis Laniel 2021-02-25  39  #define __underlying_memchr	__builtin_memchr
a28a6e860c6cf2 Francis Laniel 2021-02-25  40  #define __underlying_memcmp	__builtin_memcmp
a28a6e860c6cf2 Francis Laniel 2021-02-25  41  #define __underlying_memcpy	__builtin_memcpy
a28a6e860c6cf2 Francis Laniel 2021-02-25  42  #define __underlying_memmove	__builtin_memmove
a28a6e860c6cf2 Francis Laniel 2021-02-25  43  #define __underlying_memset	__builtin_memset
a28a6e860c6cf2 Francis Laniel 2021-02-25  44  #define __underlying_strcat	__builtin_strcat
a28a6e860c6cf2 Francis Laniel 2021-02-25  45  #define __underlying_strcpy	__builtin_strcpy
a28a6e860c6cf2 Francis Laniel 2021-02-25  46  #define __underlying_strlen	__builtin_strlen
a28a6e860c6cf2 Francis Laniel 2021-02-25  47  #define __underlying_strncat	__builtin_strncat
a28a6e860c6cf2 Francis Laniel 2021-02-25 @48  #define __underlying_strncpy	__builtin_strncpy
a28a6e860c6cf2 Francis Laniel 2021-02-25  49  #endif
a28a6e860c6cf2 Francis Laniel 2021-02-25  50  

:::::: The code at line 48 was first introduced by commit
:::::: a28a6e860c6cf231cf3c5171c75c342adcd00406 string.h: move fortified functions definitions in a dedicated header.

:::::: TO: Francis Laniel <laniel_francis@xxxxxxxxxxxxxxxxxxx>
:::::: CC: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>

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