[linux-next:pending-fixes 13358/13464] include/linux/fortify-string.h:44:33: warning: '__builtin_memcmp' specified bound 6 exceeds source size 0

[linux-next:pending-fixes 13358/13464] include/linux/fortify-string.h:44:33: warning: '__builtin_memcmp' specified bound 6 exceeds source size 0

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git pending-fixes
head:   5c5775c41d5494a213623a99b8ba1a7679efd79f
commit: 332f1795ca202489c665a75e62e18ff6284de077 [13358/13464] Bluetooth: L2CAP: Fix l2cap_global_chan_by_psm regression
config: mips-allyesconfig (https://download.01.org/0day-ci/archive/20220811/202208110453.zEneXTnn-lkp@intel.com/config)
compiler: mips-linux-gcc (GCC) 12.1.0
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/commit/?id=332f1795ca202489c665a75e62e18ff6284de077
        git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
        git fetch --no-tags linux-next pending-fixes
        git checkout 332f1795ca202489c665a75e62e18ff6284de077
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=mips SHELL=/bin/bash net/bluetooth/

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

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 include/linux/smp.h:13,
                    from arch/mips/include/asm/cpu-type.h:12,
                    from arch/mips/include/asm/timex.h:19,
                    from include/linux/timex.h:67,
                    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 net/bluetooth/l2cap_core.c:31:
   In function 'memcmp',
       inlined from 'bacmp' at include/net/bluetooth/bluetooth.h:347:9,
       inlined from 'l2cap_global_chan_by_psm' at net/bluetooth/l2cap_core.c:2003:15:
>> include/linux/fortify-string.h:44:33: warning: '__builtin_memcmp' specified bound 6 exceeds source size 0 [-Wstringop-overread]
      44 | #define __underlying_memcmp     __builtin_memcmp
         |                                 ^
   include/linux/fortify-string.h:420:16: note: in expansion of macro '__underlying_memcmp'
     420 |         return __underlying_memcmp(p, q, size);
         |                ^~~~~~~~~~~~~~~~~~~
   In function 'memcmp',
       inlined from 'bacmp' at include/net/bluetooth/bluetooth.h:347:9,
       inlined from 'l2cap_global_chan_by_psm' at net/bluetooth/l2cap_core.c:2004:15:
>> include/linux/fortify-string.h:44:33: warning: '__builtin_memcmp' specified bound 6 exceeds source size 0 [-Wstringop-overread]
      44 | #define __underlying_memcmp     __builtin_memcmp
         |                                 ^
   include/linux/fortify-string.h:420:16: note: in expansion of macro '__underlying_memcmp'
     420 |         return __underlying_memcmp(p, q, size);
         |                ^~~~~~~~~~~~~~~~~~~


vim +/__builtin_memcmp +44 include/linux/fortify-string.h

3009f891bb9f32 Kees Cook      2021-08-02  30  
a28a6e860c6cf2 Francis Laniel 2021-02-25  31  #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
a28a6e860c6cf2 Francis Laniel 2021-02-25  32  extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
a28a6e860c6cf2 Francis Laniel 2021-02-25  33  extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
a28a6e860c6cf2 Francis Laniel 2021-02-25  34  extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
a28a6e860c6cf2 Francis Laniel 2021-02-25  35  extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
a28a6e860c6cf2 Francis Laniel 2021-02-25  36  extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
a28a6e860c6cf2 Francis Laniel 2021-02-25  37  extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
a28a6e860c6cf2 Francis Laniel 2021-02-25  38  extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
a28a6e860c6cf2 Francis Laniel 2021-02-25  39  extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
a28a6e860c6cf2 Francis Laniel 2021-02-25  40  extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
a28a6e860c6cf2 Francis Laniel 2021-02-25  41  extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
a28a6e860c6cf2 Francis Laniel 2021-02-25  42  #else
a28a6e860c6cf2 Francis Laniel 2021-02-25  43  #define __underlying_memchr	__builtin_memchr
a28a6e860c6cf2 Francis Laniel 2021-02-25 @44  #define __underlying_memcmp	__builtin_memcmp
a28a6e860c6cf2 Francis Laniel 2021-02-25  45  #define __underlying_memcpy	__builtin_memcpy
a28a6e860c6cf2 Francis Laniel 2021-02-25  46  #define __underlying_memmove	__builtin_memmove
a28a6e860c6cf2 Francis Laniel 2021-02-25  47  #define __underlying_memset	__builtin_memset
a28a6e860c6cf2 Francis Laniel 2021-02-25  48  #define __underlying_strcat	__builtin_strcat
a28a6e860c6cf2 Francis Laniel 2021-02-25  49  #define __underlying_strcpy	__builtin_strcpy
a28a6e860c6cf2 Francis Laniel 2021-02-25  50  #define __underlying_strlen	__builtin_strlen
a28a6e860c6cf2 Francis Laniel 2021-02-25  51  #define __underlying_strncat	__builtin_strncat
a28a6e860c6cf2 Francis Laniel 2021-02-25  52  #define __underlying_strncpy	__builtin_strncpy
a28a6e860c6cf2 Francis Laniel 2021-02-25  53  #endif
a28a6e860c6cf2 Francis Laniel 2021-02-25  54  

:::::: The code at line 44 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>

-- 
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https://01.org/lkp