Re: [PATCH bpf-next v8 8/8] selftests/bpf: Reuse stderr parsing for libarena ASAN tests

[sashiko-bot@kernel.org]

Sashiko AI review found 1 potential issue(s):
- [Medium] The `verify_test_stderr()` function ignores unprivileged stderr test tags (`__stderr_unpriv`), silently skipping their verification.
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commit a614a51f0e77c17b24ea2c75a95abb7cf65988a1
Author: Emil Tsalapatis <emil@etsalapatis.com>

selftests/bpf: Reuse stderr parsing for libarena ASAN tests

This commit adds code to directly test the output of libarena ASAN tests by
reusing testing infrastructure from BPF streams. It introduces a new
verify_test_stderr() helper and test tags to validate stderr output against
expected messages.

> diff --git a/tools/testing/selftests/bpf/libarena/include/test_progs_compat.h b/tools/testing/selftests/bpf/libarena/include/test_progs_compat.h
> new file mode 100644
> index 0000000000000..9d431376c42f2
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/libarena/include/test_progs_compat.h
[ ... ]
> +#define __stderr(msg)		__test_tag("test_expect_stderr=" msg)
> +#define __stderr_unpriv(msg)	__test_tag("test_expect_stderr_unpriv=" msg)

[ ... ]

> diff --git a/tools/testing/selftests/bpf/test_loader.c b/tools/testing/selftests/bpf/test_loader.c
> index c4c34cae61027..ee637809a1d4e 100644
> --- a/tools/testing/selftests/bpf/test_loader.c
> +++ b/tools/testing/selftests/bpf/test_loader.c
[ ... ]
> +void verify_test_stderr(struct bpf_object *obj, struct bpf_program *prog)
> +{
> +	struct test_spec spec = {};
> +
> +	if (parse_test_spec(NULL, obj, prog, &spec))
> +		return;
> +
> +	verify_stderr(bpf_program__fd(prog), &spec.priv.stderr);

Does this code ignore unprivileged stderr test tags?

It appears that verify_test_stderr() hardcodes the use of &spec.priv.stderr.
Since it lacks an unprivileged parameter to select the unprivileged spec,
any expected messages specified via __stderr_unpriv() might be silently
ignored.

> +	free_test_spec(&spec);
> +}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260421165037.4736-1-emil@etsalapatis.com?part=8