linux-kernel - Re: [PATCH v2] selftests/seccomp: fix pointer type mismatch in UPROBE test

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Message-ID: <a5a1d7bf-04b0-43fb-8f93-781c3534d8fd@linuxfoundation.org>
Date: Wed, 3 Dec 2025 08:59:18 -0700
From: Shuah Khan <skhan@...uxfoundation.org>
To: Nirbhay Sharma <nirbhay.lkd@...il.com>, Kees Cook <kees@...nel.org>
Cc: Andy Lutomirski <luto@...capital.net>, Will Drewry <wad@...omium.org>,
 Nathan Chancellor <nathan@...nel.org>,
 Nick Desaulniers <nick.desaulniers+lkml@...il.com>,
 Bill Wendling <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>,
 linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
 bpf@...r.kernel.org, llvm@...ts.linux.dev, khalid@...nel.org,
 david.hunter.linux@...il.com, Jiri Olsa <olsajiri@...il.com>,
 sam@...too.org, shuah <shuah@...nel.org>,
 Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH v2] selftests/seccomp: fix pointer type mismatch in UPROBE
 test

On 11/25/25 04:20, Nirbhay Sharma wrote:
> 
> 
> On 10/26/25 2:42 PM, Nirbhay Sharma wrote:
>> Fix compilation error in UPROBE_setup caused by pointer type mismatch
>> in the ternary expression when compiled with -fcf-protection. The
>> probed_uprobe function pointer has the __attribute__((nocf_check))
>> attribute, which causes the conditional operator to fail when combined
>> with the regular probed_uretprobe function pointer:
>>
>>    seccomp_bpf.c:5175:74: error: pointer type mismatch in conditional
>>    expression [-Wincompatible-pointer-types]
>>
>> Cast both function pointers to 'const void *' to match the expected
>> parameter type of get_uprobe_offset(), resolving the type mismatch
>> while preserving the function selection logic.
>>
>> This error appears with compilers that enable Control Flow Integrity
>> (CFI) protection via -fcf-protection, such as Clang 19.1.2 (default
>> on Fedora).
>>
>> Signed-off-by: Nirbhay Sharma <nirbhay.lkd@...il.com>
>> ---
>>   tools/testing/selftests/seccomp/seccomp_bpf.c | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
>> index 874f17763536..e13ffe18ef95 100644
>> --- a/tools/testing/selftests/seccomp/seccomp_bpf.c
>> +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
>> @@ -5172,7 +5172,8 @@ FIXTURE_SETUP(UPROBE)
>>           ASSERT_GE(bit, 0);
>>       }
>> -    offset = get_uprobe_offset(variant->uretprobe ? probed_uretprobe : probed_uprobe);
>> +    offset = get_uprobe_offset(variant->uretprobe ?
>> +        (const void *)probed_uretprobe : (const void *)probed_uprobe);
>>       ASSERT_GE(offset, 0);
>>       if (variant->uretprobe)
> 
> Hi all,
> 
> I'm following up on this patch that fixes the pointer type mismatch in
> UPROBE_setup when building with -fcf-protection. It resolves the
> incompatible-pointer-types error seen with Clang 19.
> 
> Please let me know if there are any comments or some changes needed.
> 

Hi Kees,

Is it okay to take this patch through my tree?

thanks,
-- Shuah