On 3/6/24 2:00 AM, Kees Cook wrote:
> On Tue, Mar 05, 2024 at 07:20:27PM +0500, Muhammad Usama Anjum wrote:
>> Hello,
>>
>> I've been running execveat (execveat.c) locally on v6.1 and next-20240228.
>> It has flaky test case. There are some test cases which fail consistently.
>> The comment (not very clear) on top of failing cases is as following:
>>
>> /*
>> * Execute as a long pathname relative to "/". If this is a script,
>> * the interpreter will launch but fail to open the script because its
>> * name ("/dev/fd/5/xxx....") is bigger than PATH_MAX.
>> *
>> * The failure code is usually 127 (POSIX: "If a command is not found,
>> * the exit status shall be 127."), but some systems give 126 (POSIX:
>> * "If the command name is found, but it is not an executable utility,
>> * the exit status shall be 126."), so allow either.
>> */
>> The file name is just less than PATH_MAX (4096) and we are expecting the
>> execveat() to fail with particular 99 or 127/128 error code. But kernel is
>> returning 1 error code. Snippet from full output:
>>
>> # child 3493092 exited with 1 not 99 nor 99
>> # child 3493094 exited with 1 not 127 nor 126
>>
>> I'm not sure if test is wrong or the kernel has changed the return error codes.
>
> The error code is actually coming from the script interpreter (in this
> case, "/bin/sh"). On my system, /bin/sh is /bin/dash, and I see the
> failure. If I manually change "script" to use "#!/bin/bash", the test
> passes for me.
>
> Since lots of other selftests appears to depend on /bin/bash, I think
> the right fix is simply:
>
>
> diff --git a/tools/testing/selftests/exec/execveat.c b/tools/testing/selftests/exec/execveat.c
> index bf79d664c8e6..0546ca24f2b2 100644
> --- a/tools/testing/selftests/exec/execveat.c
> +++ b/tools/testing/selftests/exec/execveat.c
> @@ -393,7 +393,7 @@ static int run_tests(void)
> static void prerequisites(void)
> {
> int fd;
> - const char *script = "#!/bin/sh\nexit $*\n";
> + const char *script = "#!/bin/bash\nexit $*\n";
>
> /* Create ephemeral copies of files */
> exe_cp("execveat", "execveat.ephemeral");
>
>
> Can you test this and let me know if this fixes it for you?
I've tested this patch. Still getting same failures.
>
> Thanks for the report!
>
> -Kees
>
--
BR,
Muhammad Usama Anjum
