Re: [PATCH bpf-next 2/2] selftests/bpf: Cover stack frame number after scalar plus fp

[Eduard Zingerman]

On Mon, 2026-07-20 at 16:37 +0000, Yiyang Chen wrote:

...

> +++ b/tools/testing/selftests/bpf/prog_tests/verifier_basic_stack.c
> @@ -0,0 +1,28 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <test_progs.h>
> +
> +#include "cap_helpers.h"
> +#include "verifier_basic_stack.skel.h"
> +
> +void test_verifier_basic_stack(void)
> +{
> +	struct test_loader tester = {};
> +	__u64 old_caps;
> +	int err;
> +
> +	/* test_verifier tests are executed w/o CAP_SYS_ADMIN, do the same here */
> +	err = cap_disable_effective(1ULL << CAP_SYS_ADMIN, &old_caps);
> +	if (err) {
> +		PRINT_FAIL("failed to drop CAP_SYS_ADMIN: %i, %s\n", err, strerror(-err));

Why is this necessary? It should be possible to prepare a test case
demonstrating the bug w/o this change.

> +		return;
> +	}
> +
> +	test_loader__run_subtests(&tester, "verifier_basic_stack",
> +				  verifier_basic_stack__elf_bytes);
> +	test_loader_fini(&tester);
> +
> +	err = cap_enable_effective(old_caps, NULL);
> +	if (err)
> +		PRINT_FAIL("failed to restore CAP_SYS_ADMIN: %i, %s\n", err, strerror(-err));
> +}

...