linux-kernel - Re: [PATCH v3 06/11] selftests/mm: fix two -Wformat-security warnings in uffd builds

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Date:   Tue, 6 Jun 2023 12:54:30 +0500
From:   Muhammad Usama Anjum <usama.anjum@...labora.com>
To:     John Hubbard <jhubbard@...dia.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Muhammad Usama Anjum <usama.anjum@...labora.com>,
        David Hildenbrand <david@...hat.com>,
        Peter Xu <peterx@...hat.com>, Shuah Khan <shuah@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>, linux-mm@...ck.org,
        linux-kselftest@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 06/11] selftests/mm: fix two -Wformat-security warnings
 in uffd builds

On 6/6/23 12:16 PM, John Hubbard wrote:
> The uffd tests generate two compile time warnings from clang's
> -Wformat-security setting. These trigger at the call sites for
> uffd_test_start() and uffd_test_skip().
> 
> 1) Fix the uffd_test_start() issue by removing the intermediate
> test_name variable (thanks to David Hildenbrand for showing how to do
> this).
> 
> 2) Fix the uffd_test_skip() issue by observing that there is no need for
> a macro and a variable args approach, because all callers of
> uffd_test_skip() pass in a simple char* string, without any format
> specifiers. So just change uffd_test_skip() into a regular C function.
> 
> Reviewed-by: David Hildenbrand <david@...hat.com>
> Reviewed-by: Peter Xu <peterx@...hat.com>
> Signed-off-by: John Hubbard <jhubbard@...dia.com>
Tested-by: Muhammad Usama Anjum <usama.anjum@...labora.com>

> ---
>  tools/testing/selftests/mm/uffd-unit-tests.c | 16 ++++++----------
>  1 file changed, 6 insertions(+), 10 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c
> index 269c86768a02..04d91f144d1c 100644
> --- a/tools/testing/selftests/mm/uffd-unit-tests.c
> +++ b/tools/testing/selftests/mm/uffd-unit-tests.c
> @@ -109,12 +109,11 @@ static void uffd_test_pass(void)
>  		ksft_inc_fail_cnt();		\
>  	} while (0)
>  
> -#define  uffd_test_skip(...)  do {		\
> -		printf("skipped [reason: ");	\
> -		printf(__VA_ARGS__);		\
> -		printf("]\n");			\
> -		ksft_inc_xskip_cnt();		\
> -	} while (0)
> +static void uffd_test_skip(const char *message)
> +{
> +	printf("skipped [reason: %s]\n", message);
> +	ksft_inc_xskip_cnt();
> +}
>  
>  /*
>   * Returns 1 if specific userfaultfd supported, 0 otherwise.  Note, we'll
> @@ -1149,7 +1148,6 @@ int main(int argc, char *argv[])
>  	uffd_test_case_t *test;
>  	mem_type_t *mem_type;
>  	uffd_test_args_t args;
> -	char test_name[128];
>  	const char *errmsg;
>  	int has_uffd, opt;
>  	int i, j;
> @@ -1192,10 +1190,8 @@ int main(int argc, char *argv[])
>  			mem_type = &mem_types[j];
>  			if (!(test->mem_targets & mem_type->mem_flag))
>  				continue;
> -			snprintf(test_name, sizeof(test_name),
> -				 "%s on %s", test->name, mem_type->name);
>  
> -			uffd_test_start(test_name);
> +			uffd_test_start("%s on %s", test->name, mem_type->name);
>  			if (!uffd_feature_supported(test)) {
>  				uffd_test_skip("feature missing");
>  				continue;

-- 
BR,
Muhammad Usama Anjum