linux-kernel - include/linux/fortify-string.h:59:33: warning: '__builtin_memset' specified bound 18446744073709551615 exceeds maximum object size 9223372036854775807

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Message-ID: <202310181852.t3zhZN02-lkp@intel.com>
Date:   Wed, 18 Oct 2023 18:59:18 +0800
From:   kernel test robot <lkp@...el.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: include/linux/fortify-string.h:59:33: warning: '__builtin_memset'
 specified bound 18446744073709551615 exceeds maximum object size
 9223372036854775807

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   06dc10eae55b5ceabfef287a7e5f16ceea204aa0
commit: 439a1bcac648fe9b59210cde8991fb2acf37bdab fortify: Use __builtin_dynamic_object_size() when available
date:   10 months ago
config: s390-randconfig-r002-20230326 (https://download.01.org/0day-ci/archive/20231018/202310181852.t3zhZN02-lkp@intel.com/config)
compiler: s390-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231018/202310181852.t3zhZN02-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310181852.t3zhZN02-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 include/linux/lockdep.h:14,
                    from include/linux/spinlock.h:63,
                    from include/linux/mmzone.h:8,
                    from include/linux/gfp.h:7,
                    from include/linux/slab.h:15,
                    from drivers/misc/lkdtm/usercopy.c:7:
   drivers/misc/lkdtm/usercopy.c: In function 'do_usercopy_slab_size':
>> include/linux/fortify-string.h:59:33: warning: '__builtin_memset' specified bound 18446744073709551615 exceeds maximum object size 9223372036854775807 [-Wstringop-overflow=]
      59 | #define __underlying_memset     __builtin_memset
         |                                 ^
   include/linux/fortify-string.h:453:9: note: in expansion of macro '__underlying_memset'
     453 |         __underlying_memset(p, c, __fortify_size);                      \
         |         ^~~~~~~~~~~~~~~~~~~
   include/linux/fortify-string.h:461:25: note: in expansion of macro '__fortify_memset_chk'
     461 | #define memset(p, c, s) __fortify_memset_chk(p, c, s,                   \
         |                         ^~~~~~~~~~~~~~~~~~~~
   drivers/misc/lkdtm/usercopy.c:157:9: note: in expansion of macro 'memset'
     157 |         memset(one, 'A', size);
         |         ^~~~~~


vim +/__builtin_memset +59 include/linux/fortify-string.h

78a498c3a227f2 Alexander Potapenko 2022-10-24  46  
78a498c3a227f2 Alexander Potapenko 2022-10-24  47  #if defined(__SANITIZE_MEMORY__)
78a498c3a227f2 Alexander Potapenko 2022-10-24  48  /*
78a498c3a227f2 Alexander Potapenko 2022-10-24  49   * For KMSAN builds all memcpy/memset/memmove calls should be replaced by the
78a498c3a227f2 Alexander Potapenko 2022-10-24  50   * corresponding __msan_XXX functions.
78a498c3a227f2 Alexander Potapenko 2022-10-24  51   */
78a498c3a227f2 Alexander Potapenko 2022-10-24  52  #include <linux/kmsan_string.h>
78a498c3a227f2 Alexander Potapenko 2022-10-24  53  #define __underlying_memcpy	__msan_memcpy
78a498c3a227f2 Alexander Potapenko 2022-10-24  54  #define __underlying_memmove	__msan_memmove
78a498c3a227f2 Alexander Potapenko 2022-10-24  55  #define __underlying_memset	__msan_memset
78a498c3a227f2 Alexander Potapenko 2022-10-24  56  #else
a28a6e860c6cf2 Francis Laniel      2021-02-25  57  #define __underlying_memcpy	__builtin_memcpy
a28a6e860c6cf2 Francis Laniel      2021-02-25  58  #define __underlying_memmove	__builtin_memmove
a28a6e860c6cf2 Francis Laniel      2021-02-25 @59  #define __underlying_memset	__builtin_memset
78a498c3a227f2 Alexander Potapenko 2022-10-24  60  #endif
78a498c3a227f2 Alexander Potapenko 2022-10-24  61  

:::::: The code at line 59 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>

-- 
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https://github.com/intel/lkp-tests/wiki