linux-kernel - Re: [PATCH] selftests/harness: fix many "format string is empty" warnings

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <26435372-004c-4f8d-b16e-a26a1806147e@nvidia.com>
Date: Wed, 1 May 2024 10:14:11 -0700
From: John Hubbard <jhubbard@...dia.com>
To: Nathan Chancellor <nathan@...nel.org>
Cc: Shuah Khan <shuah@...nel.org>, linux-kselftest@...r.kernel.org,
 LKML <linux-kernel@...r.kernel.org>, Valentin Obst <kernel@...entinobst.de>,
 Kees Cook <keescook@...omium.org>, Nick Desaulniers
 <ndesaulniers@...gle.com>, Justin Stitt <justinstitt@...gle.com>,
 Bill Wendling <morbo@...gle.com>
Subject: Re: [PATCH] selftests/harness: fix many "format string is empty"
 warnings

On 5/1/24 8:13 AM, Nathan Chancellor wrote:
> Hi John,
> 
> On Tue, Apr 30, 2024 at 07:08:13PM -0700, John Hubbard wrote:
>> In order to build with clang at all, in order to see these symptoms, one
>> must first apply Valentin Obst's build fix for LLVM [1]. Once that is
>> done, then when building with clang, via:
>>
>>      make LLVM=1 -C tools/testing/selftests
>>
>> ...clang emits a "format string is empty" warning. (gcc also emits a
>> similar warning.)
> 
> The warning you are describing here sounds like the same exact one that
> commit caed8eba2215 ("selftests: kselftest_harness: fix Clang warning
> about zero-length format") should have addressed in 6.9-rc5. Is this
> patch actually necessary?

Apparently not!

> 
>> Fix by passing NULL, instead of "", for the msg argument to
> 
> Because this text is describing what was done in caed8eba2215...

Yes. I took a while between discovering the issue, and posting a fix, I
think that's why.

> 
>> ksft_test_result_code(). This removes dozens of warnings and a few
>> errors (some tests have -Werror set).
>>
>> [1] https://lore.kernel.org/all/20240329-selftests-libmk-llvm-rfc-v1-1-2f9ed7d1c49f@valentinobst.de/
>>
>> Cc: Valentin Obst <kernel@...entinobst.de>
>> Cc: Kees Cook <keescook@...omium.org>
>> Cc: Nick Desaulniers <ndesaulniers@...gle.com>
>> Cc: Nathan Chancellor <nathan@...nel.org>
>> Cc: Shuah Khan <shuah@...nel.org>
>> Cc: Justin Stitt <justinstitt@...gle.com>
>> Cc: Bill Wendling <morbo@...gle.com>
>> Signed-off-by: John Hubbard <jhubbard@...dia.com>
>> ---
>>   tools/testing/selftests/kselftest_harness.h | 6 ++++--
>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h
>> index d98702b6955d..456b8694e678 100644
>> --- a/tools/testing/selftests/kselftest_harness.h
>> +++ b/tools/testing/selftests/kselftest_harness.h
>> @@ -1207,8 +1207,10 @@ void __run_test(struct __fixture_metadata *f,
>>   	else
>>   		diagnostic = "unknown";
>>   
>> -	ksft_test_result_code(t->exit_code, test_name,
>> -			      diagnostic ? "%s" : NULL, diagnostic);
>> +	if (diagnostic)
>> +		ksft_test_result_code(t->exit_code, test_name, "%s", diagnostic);
>> +	else
>> +		ksft_test_result_code(t->exit_code, test_name, NULL);
> 
> but this diff is not doing that because it is based on a tree that has
> caed8eba2215; instead, it appears to be a completely identical
> transformation?
> 

It's nice to see that someone else had the same fix, anyway. Sorry
about the noise, and yes let's please just drop this one.

thanks,
-- 
John Hubbard
NVIDIA