Commit f904c678 authored by David Vernet's avatar David Vernet Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add test for non-NULLable PTR_TO_BTF_IDs 



In a recent patch, we taught the verifier that trusted PTR_TO_BTF_ID can
never be NULL. This prevents the verifier from incorrectly failing to
load certain programs where it gets confused and thinks a reference
isn't dropped because it incorrectly assumes that a branch exists in
which a NULL PTR_TO_BTF_ID pointer is never released.

This patch adds a testcase that verifies this cannot happen.

Signed-off-by: default avatarDavid Vernet <void@manifault.com>
Acked-by: default avatarStanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230602150112.1494194-2-void@manifault.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 51302c95

tools/testing/selftests/bpf/prog_tests/cpumask.c

+1 −0
Original line number Diff line number Diff line
@@ -70,5 +70,6 @@ void test_cpumask(void) 
		verify_success(cpumask_success_testcases[i]);

	}



	RUN_TESTS(cpumask_success);

	RUN_TESTS(cpumask_failure);

}

tools/testing/selftests/bpf/progs/cpumask_success.c

+24 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
#include <bpf/bpf_tracing.h>

#include <bpf/bpf_helpers.h>



#include "bpf_misc.h"

#include "cpumask_common.h"



char _license[] SEC("license") = "GPL";
@@ -426,3 +427,26 @@ int BPF_PROG(test_global_mask_rcu, struct task_struct *task, u64 clone_flags) 


	return 0;

}



SEC("tp_btf/task_newtask")

__success

int BPF_PROG(test_refcount_null_tracking, struct task_struct *task, u64 clone_flags)

{

	struct bpf_cpumask *mask1, *mask2;



	mask1 = bpf_cpumask_create();

	mask2 = bpf_cpumask_create();



	if (!mask1 || !mask2)

		goto free_masks_return;



	bpf_cpumask_test_cpu(0, (const struct cpumask *)mask1);

	bpf_cpumask_test_cpu(0, (const struct cpumask *)mask2);



free_masks_return:

	if (mask1)

		bpf_cpumask_release(mask1);

	if (mask2)

		bpf_cpumask_release(mask2);

	return 0;

}