netdev - [net-next:master 75/126] include/linux/fortify-string.h:27:30: warning: '__builtin_strncpy' output truncated before terminating nul copying as many bytes from a string as its length

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Date:   Sat, 15 May 2021 09:28:53 +0800
From:   kernel test robot <lkp@...el.com>
To:     Huazhong Tan <tanhuazhong@...wei.com>
Cc:     kbuild-all@...ts.01.org, netdev@...r.kernel.org
Subject: [net-next:master 75/126] include/linux/fortify-string.h:27:30:
 warning: '__builtin_strncpy' output truncated before terminating nul copying
 as many bytes from a string as its length

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git master
head:   77091933e453a258bbe9ff2aeb1c8d6fc1db7ef9
commit: 1556ea9120ffcf4faf7ac6b62a6e28216f260a23 [75/126] net: hns3: refactor dump mac list of debugfs
config: mips-allyesconfig (attached as .config)
compiler: mips-linux-gcc (GCC) 9.3.0
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/davem/net-next.git/commit/?id=1556ea9120ffcf4faf7ac6b62a6e28216f260a23
        git remote add net-next https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git
        git fetch --no-tags net-next master
        git checkout 1556ea9120ffcf4faf7ac6b62a6e28216f260a23
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross W=1 ARCH=mips 

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

All warnings (new ones prefixed by >>):

   In file included from include/linux/string.h:269,
                    from include/linux/bitmap.h:10,
                    from include/linux/cpumask.h:12,
                    from arch/mips/include/asm/processor.h:15,
                    from arch/mips/include/asm/thread_info.h:16,
                    from include/linux/thread_info.h:59,
                    from include/asm-generic/current.h:5,
                    from ./arch/mips/include/generated/asm/current.h:1,
                    from include/linux/sched.h:12,
                    from include/linux/ratelimit.h:6,
                    from include/linux/dev_printk.h:16,
                    from include/linux/device.h:15,
                    from drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_debugfs.c:4:
   In function 'strncpy',
       inlined from 'hclge_dbg_fill_content.constprop' at drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_debugfs.c:88:4:
>> include/linux/fortify-string.h:27:30: warning: '__builtin_strncpy' output truncated before terminating nul copying as many bytes from a string as its length [-Wstringop-truncation]
      27 | #define __underlying_strncpy __builtin_strncpy
         |                              ^
   include/linux/fortify-string.h:38:9: note: in expansion of macro '__underlying_strncpy'
      38 |  return __underlying_strncpy(p, q, size);
         |         ^~~~~~~~~~~~~~~~~~~~
   drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_debugfs.c: In function 'hclge_dbg_fill_content.constprop':
   include/linux/fortify-string.h:25:29: note: length computed here
      25 | #define __underlying_strlen __builtin_strlen
         |                             ^
   include/linux/fortify-string.h:60:10: note: in expansion of macro '__underlying_strlen'
      60 |   return __underlying_strlen(p);
         |          ^~~~~~~~~~~~~~~~~~~


vim +/__builtin_strncpy +27 include/linux/fortify-string.h

a28a6e860c6cf2 Francis Laniel 2021-02-25   4  
a28a6e860c6cf2 Francis Laniel 2021-02-25   5  
a28a6e860c6cf2 Francis Laniel 2021-02-25   6  #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
a28a6e860c6cf2 Francis Laniel 2021-02-25   7  extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
a28a6e860c6cf2 Francis Laniel 2021-02-25   8  extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
a28a6e860c6cf2 Francis Laniel 2021-02-25   9  extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
a28a6e860c6cf2 Francis Laniel 2021-02-25  10  extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
a28a6e860c6cf2 Francis Laniel 2021-02-25  11  extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
a28a6e860c6cf2 Francis Laniel 2021-02-25  12  extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
a28a6e860c6cf2 Francis Laniel 2021-02-25  13  extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
a28a6e860c6cf2 Francis Laniel 2021-02-25  14  extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
a28a6e860c6cf2 Francis Laniel 2021-02-25  15  extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
a28a6e860c6cf2 Francis Laniel 2021-02-25  16  extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
a28a6e860c6cf2 Francis Laniel 2021-02-25  17  #else
a28a6e860c6cf2 Francis Laniel 2021-02-25  18  #define __underlying_memchr	__builtin_memchr
a28a6e860c6cf2 Francis Laniel 2021-02-25  19  #define __underlying_memcmp	__builtin_memcmp
a28a6e860c6cf2 Francis Laniel 2021-02-25  20  #define __underlying_memcpy	__builtin_memcpy
a28a6e860c6cf2 Francis Laniel 2021-02-25  21  #define __underlying_memmove	__builtin_memmove
a28a6e860c6cf2 Francis Laniel 2021-02-25  22  #define __underlying_memset	__builtin_memset
a28a6e860c6cf2 Francis Laniel 2021-02-25  23  #define __underlying_strcat	__builtin_strcat
a28a6e860c6cf2 Francis Laniel 2021-02-25  24  #define __underlying_strcpy	__builtin_strcpy
a28a6e860c6cf2 Francis Laniel 2021-02-25  25  #define __underlying_strlen	__builtin_strlen
a28a6e860c6cf2 Francis Laniel 2021-02-25  26  #define __underlying_strncat	__builtin_strncat
a28a6e860c6cf2 Francis Laniel 2021-02-25 @27  #define __underlying_strncpy	__builtin_strncpy
a28a6e860c6cf2 Francis Laniel 2021-02-25  28  #endif
a28a6e860c6cf2 Francis Laniel 2021-02-25  29  

:::::: The code at line 27 was first introduced by commit
:::::: a28a6e860c6cf231cf3c5171c75c342adcd00406 string.h: move fortified functions definitions in a dedicated header.

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

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

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