Re: [PATCH bpf-next v3 4/4] selftests/bpf: Check for flag presence in bpf_program__flags()

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Missing NULL check for `prog` before calling `bpf_program__flags()`.
--

commit 05df19ea2fe700cefa5c96da6572795ffbe95855
Author: Toke Høiland-Jørgensen <toke@redhat.com>
Date:   Tue Sep 1 08:46:57 2026 +0000

selftests/bpf: Check for flag presence in bpf_program__flags()

This commit adds assertions to verify that the BPF_F_XDP_HAS_FRAGS and
BPF_F_SLEEPABLE flags are present in bpf_program__flags() when opening BPF
programs that have these flags in their section definitions.

> diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_adjust_frags.c b/tools/testing/selftests/bpf/prog_tests/xdp_adjust_frags.c
> index fce203640f8cf..a894b1ab46f4e 100644
> --- a/tools/testing/selftests/bpf/prog_tests/xdp_adjust_frags.c
> +++ b/tools/testing/selftests/bpf/prog_tests/xdp_adjust_frags.c
> @@ -18,6 +18,9 @@ static void test_xdp_update_frags(void)
>  		return;
>  
>  	prog = bpf_object__next_program(obj, NULL);
> +	ASSERT_EQ(bpf_program__flags(prog) & BPF_F_XDP_HAS_FRAGS,
> +		  BPF_F_XDP_HAS_FRAGS, "frags in program flags");
> +

[Severity: Medium]
Is a NULL check needed for prog here?

If the BPF object file test_xdp_update_frags.bpf.o is valid but contains no
programs (for instance, due to a build issue or a stripped ELF),
bpf_object__next_program() will return NULL. The prog pointer is then passed
directly to bpf_program__flags(), which will unconditionally dereference it
and cause a segmentation fault in the test suite.

Prior to this patch, prog was safely passed down to bpf_program__fd(), which
gracefully handled the NULL by returning -EINVAL and failing the test cleanly.
Would it be safer to check prog with ASSERT_OK_PTR() before attempting to
verify its flags?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260901-libbpf-frags-flags-v3-0-4eb6f14968b0@redhat.com?part=4