[FFmpeg-devel] [PATCH] tests/checkasm: prevent a segmentation fault when calling strncmp()

[Martin Storsjö]

On Thu, 16 Jan 2025, Sean McGovern wrote:

> The POSIX specification for strncmp()[1] leaves this behaviour as
> undefined if either pointer argument is NULL.
>
> Prevent a segmentation fault by ensuring 'arg' is non-NULL.
>
> [1] https://pubs.opengroup.org/onlinepubs/9799919799/functions/strncmp.html
> ---
> tests/checkasm/checkasm.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tests/checkasm/checkasm.c b/tests/checkasm/checkasm.c
> index 14742081ca..4270ed170a 100644
> --- a/tests/checkasm/checkasm.c
> +++ b/tests/checkasm/checkasm.c
> @@ -952,7 +952,7 @@ int main(int argc, char *argv[])
>     }
>
>     for (i = 1; i < argc; i++) {
> -        const char *arg = argv[i];
> +        const char *arg = argv[i] != NULL ? argv[i] : "";
>         unsigned long l;

This feels like less of an issue with strncmp, and more of an issue with 
the spec for main() and argc/argv; how do you do to end up with a NULL 
entry in argv[i] for 0 <= i < argc?

// Martin