Re: [PATCH bpf-next v2 6/9] selftests: bpf: fix test_kfunc_dynptr_param

["Emil Tsalapatis" <emil@etsalapatis.com>]

On Wed Dec 31, 2025 at 12:08 PM EST, Puranjay Mohan wrote:
> As verifier now assumes that all kfuncs only takes trusted pointer
> arguments, passing 0 (NULL) to a kfunc that doesn't mark the argument as
> __nullable or __opt will be rejected with a failure message of: Possibly
> NULL pointer passed to trusted arg<n>
>
> Pass a non-null value to the kfunc to test the expected failure mode.
>
> Signed-off-by: Puranjay Mohan <puranjay@kernel.org>

Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>

> ---
>  tools/testing/selftests/bpf/progs/test_kfunc_dynptr_param.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/progs/test_kfunc_dynptr_param.c b/tools/testing/selftests/bpf/progs/test_kfunc_dynptr_param.c
> index 061befb004c2..d249113ed657 100644
> --- a/tools/testing/selftests/bpf/progs/test_kfunc_dynptr_param.c
> +++ b/tools/testing/selftests/bpf/progs/test_kfunc_dynptr_param.c
> @@ -48,10 +48,9 @@ SEC("?lsm.s/bpf")
>  __failure __msg("arg#0 expected pointer to stack or const struct bpf_dynptr")
>  int BPF_PROG(not_ptr_to_stack, int cmd, union bpf_attr *attr, unsigned int size, bool kernel)
>  {
> -	unsigned long val = 0;
> +	static struct bpf_dynptr val;
>  
> -	return bpf_verify_pkcs7_signature((struct bpf_dynptr *)val,
> -					  (struct bpf_dynptr *)val, NULL);
> +	return bpf_verify_pkcs7_signature(&val, &val, NULL);
>  }
>  
>  SEC("lsm.s/bpf")