linux-hardening - Re: [PATCH] lib/test_string.c: Add test for strlen()

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Date:   Sun, 30 Jan 2022 12:35:13 -0800
From:   Kees Cook <keescook@...omium.org>
To:     kernel test robot <lkp@...el.com>
Cc:     kbuild-all@...ts.01.org, Geert Uytterhoeven <geert@...ux-m68k.org>,
        Peter Rosin <peda@...ntia.se>,
        Andy Shevchenko <andy@...nel.org>,
        Matteo Croce <mcroce@...rosoft.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH] lib/test_string.c: Add test for strlen()

On Mon, Jan 31, 2022 at 04:13:30AM +0800, kernel test robot wrote:
> Hi Kees,
> 
> I love your patch! Yet something to improve:
> 
> [auto build test ERROR on linux/master]
> [also build test ERROR on linus/master kees/for-next/pstore v5.17-rc2 next-20220128]
> [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]
> 
> url:    https://github.com/0day-ci/linux/commits/Kees-Cook/lib-test_string-c-Add-test-for-strlen/20220131-023726
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 2c271fe77d52a0555161926c232cd5bc07178b39
> config: sh-allmodconfig (https://download.01.org/0day-ci/archive/20220131/202201310303.HQlCsvvd-lkp@intel.com/config)
> compiler: sh4-linux-gcc (GCC) 11.2.0
> 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/0day-ci/linux/commit/d22fe883339c5141953dbca980b51466ac3e2329
>         git remote add linux-review https://github.com/0day-ci/linux
>         git fetch --no-tags linux-review Kees-Cook/lib-test_string-c-Add-test-for-strlen/20220131-023726
>         git checkout d22fe883339c5141953dbca980b51466ac3e2329
>         # save the config file to linux build tree
>         mkdir build_dir
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=sh SHELL=/bin/bash M=lib/
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@...el.com>
> 
> All errors (new ones prefixed by >>):
> 
> >> lib/test_string.c:188:30: error: initializer element is not constant
>      188 | static const int strlen_ce = strlen("tada, a constant expression");
>          |                              ^~~~~~

Thanks; this is expected -- the strlen() in -next is currently broken
(and will be fixed in the next -next).

-Kees

> 
> 
> vim +188 lib/test_string.c
> 
>    181	
>    182	/*
>    183	 * Unlike many other string functions, strlen() can be used in
>    184	 * static initializers when string lengths are known at compile
>    185	 * time. (i.e. Under these conditions, strlen() is a constant
>    186	 * expression.) Make sure it can be used this way.
>    187	 */
>  > 188	static const int strlen_ce = strlen("tada, a constant expression");
>    189	
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

-- 
Kees Cook