[PATCH v4 bpf-next 1/3] libbpf: disassociate section handler on explicit bpf_program__set_type() call

Andrii Nakryiko
2023-03-27T18:52:24Z

If user explicitly overrides programs's type with
bpf_program__set_type() API call, we need to disassociate whatever
SEC_DEF handler libbpf determined initially based on program's SEC()
definition, as it's not goind to be valid anymore and could lead to
crashes and/or confusing failures.

Also, fix up bpf_prog_test_load() helper in selftests/bpf, which is
force-setting program type (even if that's completely unnecessary; this
is quite a legacy piece of code), and thus should expect auto-attach to
not work, yet one of the tests explicitly relies on auto-attach for
testing.

Instead, force-set program type only if it differs from the desired one.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
tools/lib/bpf/libbpf.c | 1 +
tools/testing/selftests/bpf/testing_helpers.c | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 15737d7b5a28..49cd304ae3bc 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -8468,6 +8468,7 @@ int bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type)
return libbpf_err(-EBUSY);

prog->type = type;
+ prog->sec_def = NULL;
return 0;
}

diff --git a/tools/testing/selftests/bpf/testing_helpers.c b/tools/testing/selftests/bpf/testing_helpers.c
index 6c44153755e6..ecfea13f938b 100644
--- a/tools/testing/selftests/bpf/testing_helpers.c
+++ b/tools/testing/selftests/bpf/testing_helpers.c
@@ -195,7 +195,7 @@ int bpf_prog_test_load(const char *file, enum bpf_prog_type type,
goto err_out;
}

- if (type != BPF_PROG_TYPE_UNSPEC)
+ if (type != BPF_PROG_TYPE_UNSPEC && bpf_program__type(prog) != type)
bpf_program__set_type(prog, type);

flags = bpf_program__flags(prog) | BPF_F_TEST_RND_HI32;
--
2.34.1