Re: [PATCH] fortify: turn strlen() into an inline function using __builtin_constant_p()

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

Hi Vincent,

kernel test robot noticed the following build errors:

[auto build test ERROR on 9d89551994a430b50c4fffcb1e617a057fa76e20]

url:    https://github.com/intel-lab-lkp/linux/commits/Vincent-Mailhol/fortify-turn-strlen-into-an-inline-function-using-__builtin_constant_p/20250108-223159
base:   9d89551994a430b50c4fffcb1e617a057fa76e20
patch link:    https://lore.kernel.org/r/20250108-strlen_use_builtin_constant_p-v1-1-611b52e80a9f%40wanadoo.fr
patch subject: [PATCH] fortify: turn strlen() into an inline function using __builtin_constant_p()
config: x86_64-randconfig-001-20250109 (https://download.01.org/0day-ci/archive/20250109/202501092158.Gp5vNOZy-lkp@intel.com/config)
compiler: clang version 19.1.3 (https://github.com/llvm/llvm-project ab51eccf88f5321e7c60591c5546b254b6afab99)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250109/202501092158.Gp5vNOZy-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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202501092158.Gp5vNOZy-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from scripts/mod/devicetable-offsets.c:3:
   In file included from include/linux/mod_devicetable.h:14:
   In file included from include/linux/uuid.h:11:
   In file included from include/linux/string.h:389:
>> include/linux/fortify-string.h:272:17: error: redeclaration of 'strlen' must not have the 'overloadable' attribute
     272 | __kernel_size_t strlen(const char *p)
         |                 ^
   include/linux/string.h:200:24: note: previous unmarked overload of function is here
     200 | extern __kernel_size_t strlen(const char *);
         |                        ^
   1 error generated.
   make[3]: *** [scripts/Makefile.build:102: scripts/mod/devicetable-offsets.s] Error 1 shuffle=1556232066
   make[3]: Target 'scripts/mod/' not remade because of errors.
   make[2]: *** [Makefile:1262: prepare0] Error 2 shuffle=1556232066
   make[2]: Target 'prepare' not remade because of errors.
   make[1]: *** [Makefile:251: __sub-make] Error 2 shuffle=1556232066
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [Makefile:251: __sub-make] Error 2 shuffle=1556232066
   make: Target 'prepare' not remade because of errors.


vim +272 include/linux/fortify-string.h

   257	
   258	/**
   259	 * strlen - Return count of characters in a NUL-terminated string
   260	 *
   261	 * @p: pointer to NUL-terminated string to count.
   262	 *
   263	 * Do not use this function unless the string length is known at
   264	 * compile-time. When @p is unterminated, this function may crash
   265	 * or return unexpected counts that could lead to memory content
   266	 * exposures. Prefer strnlen().
   267	 *
   268	 * Returns number of characters in @p (NOT including the final NUL).
   269	 *
   270	 */
   271	__FORTIFY_INLINE __diagnose_as(__builtin_strlen, 1)
 > 272	__kernel_size_t strlen(const char *p)
   273	{
   274		if (__builtin_constant_p(__builtin_strlen(p)))
   275			return __builtin_strlen(p);
   276		return __fortify_strlen(p);
   277	}
   278	

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