Re: [PATCH bpf-next v2 2/4] bpf: selftests: 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 pointer check on the result of bpf_object__next_program() causes a potential test crash.
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commit 357b58adee859a9375d4063d6f64aa4a923e7790
Author: Toke Høiland-Jørgensen <toke@redhat.com>

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

This commit adds checks to verify that the BPF_F_XDP_HAS_FRAGS and
BPF_F_SLEEPABLE flags are correctly exposed by bpf_program__flags(). It
introduces assertions in multiple selftests immediately after retrieving
the BPF program structures.

> 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]
What happens if bpf_object__next_program() returns a NULL pointer here?

The prog pointer is passed directly to bpf_program__flags(), which
unconditionally dereferences it. While the object file is expected to contain
programs during normal builds, if it does not, could this cause the test suite
to hard crash with a segmentation fault instead of failing gracefully?

Prior to this patch, a NULL prog would be handled more safely, as the later
call to bpf_program__fd() explicitly checks for NULL and returns an error
code. 

Does it make sense to add a check like ASSERT_OK_PTR(prog, "prog") before
accessing its flags?

[ ... ]

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Sashiko AI review · https://sashiko.dev/#/patchset/20260831132648.65843-1-toke@redhat.com?part=2