Re: [PATCH 3/9] string: Add Kunit tests for strcat() family

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

Hi Kees,

kernel test robot noticed the following build warnings:

[auto build test WARNING on kees/for-next/hardening]
[also build test WARNING on kees/for-next/pstore kees/for-next/kspp akpm-mm/mm-everything linus/master v6.3-rc5 next-20230405]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Kees-Cook/kunit-tool-Enable-CONFIG_FORTIFY_SOURCE-under-UML/20230406-081014
base:   https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/hardening
patch link:    https://lore.kernel.org/r/20230406000212.3442647-3-keescook%40chromium.org
patch subject: [PATCH 3/9] string: Add Kunit tests for strcat() family
config: riscv-randconfig-r042-20230403 (https://download.01.org/0day-ci/archive/20230406/202304061243.Bx5SK1xq-lkp@intel.com/config)
compiler: riscv64-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://github.com/intel-lab-lkp/linux/commit/1cdc1d7eeb09497f84367bfc2919d5fcc380e454
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Kees-Cook/kunit-tool-Enable-CONFIG_FORTIFY_SOURCE-under-UML/20230406-081014
        git checkout 1cdc1d7eeb09497f84367bfc2919d5fcc380e454
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=riscv olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304061243.Bx5SK1xq-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from include/linux/err.h:5,
                    from include/kunit/assert.h:12,
                    from include/kunit/test.h:12,
                    from lib/strcat_kunit.c:8:
   lib/strcat_kunit.c: In function 'strncat_test':
>> lib/strcat_kunit.c:52:33: warning: 'strncat' output truncated copying 2 bytes from a string of length 4 [-Wstringop-truncation]
      52 |         KUNIT_EXPECT_TRUE(test, strncat(dest, "ABCD", 2) == dest);
         |                                 ^~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/compiler.h:77:45: note: in definition of macro 'likely'
      77 | # define likely(x)      __builtin_expect(!!(x), 1)
         |                                             ^
   include/kunit/test.h:545:9: note: in expansion of macro 'KUNIT_UNARY_ASSERTION'
     545 |         KUNIT_UNARY_ASSERTION(test,                                            \
         |         ^~~~~~~~~~~~~~~~~~~~~
   include/kunit/test.h:736:9: note: in expansion of macro 'KUNIT_TRUE_MSG_ASSERTION'
     736 |         KUNIT_TRUE_MSG_ASSERTION(test,                                         \
         |         ^~~~~~~~~~~~~~~~~~~~~~~~
   include/kunit/test.h:733:9: note: in expansion of macro 'KUNIT_EXPECT_TRUE_MSG'
     733 |         KUNIT_EXPECT_TRUE_MSG(test, condition, NULL)
         |         ^~~~~~~~~~~~~~~~~~~~~
   lib/strcat_kunit.c:52:9: note: in expansion of macro 'KUNIT_EXPECT_TRUE'
      52 |         KUNIT_EXPECT_TRUE(test, strncat(dest, "ABCD", 2) == dest);
         |         ^~~~~~~~~~~~~~~~~


vim +/strncat +52 lib/strcat_kunit.c

    29	
    30	static void strncat_test(struct kunit *test)
    31	{
    32		char dest[8];
    33	
    34		/* Destination is terminated. */
    35		memset(dest, 0, sizeof(dest));
    36		KUNIT_EXPECT_EQ(test, strlen(dest), 0);
    37		/* Empty copy of size 0 does nothing. */
    38		KUNIT_EXPECT_TRUE(test, strncat(dest, "", 0) == dest);
    39		KUNIT_EXPECT_STREQ(test, dest, "");
    40		/* Empty copy of size 1 does nothing too. */
    41		KUNIT_EXPECT_TRUE(test, strncat(dest, "", 1) == dest);
    42		KUNIT_EXPECT_STREQ(test, dest, "");
    43		/* Copy of max 0 characters should do nothing. */
    44		KUNIT_EXPECT_TRUE(test, strncat(dest, "asdf", 0) == dest);
    45		KUNIT_EXPECT_STREQ(test, dest, "");
    46	
    47		/* 4 characters copied in, even if max is 8. */
    48		KUNIT_EXPECT_TRUE(test, strncat(dest, "four\000123", 8) == dest);
    49		KUNIT_EXPECT_STREQ(test, dest, "four");
    50		KUNIT_EXPECT_EQ(test, dest[5], '\0');
    51		/* 2 characters copied in okay, 2 ignored. */
  > 52		KUNIT_EXPECT_TRUE(test, strncat(dest, "ABCD", 2) == dest);
    53		KUNIT_EXPECT_STREQ(test, dest, "fourAB");
    54	}
    55	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests