Add a test case to verify the fix for "prog->aux->dst_trampoline and tgt_prog is NULL" branch in bpf_tracing_prog_attach. The sequence of events: 1. load rawtp program 2. load fentry program with rawtp as target_fd 3. create tracing link for fentry program with target_fd = 0 4. repeat 3 Signed-off-by: Dmitrii Dolgov <9erthalion6@xxxxxxxxx> --- .../bpf/prog_tests/recursive_attach.c | 48 +++++++++++++++++++ .../bpf/progs/fentry_recursive_target.c | 11 +++++ 2 files changed, 59 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/recursive_attach.c b/tools/testing/selftests/bpf/prog_tests/recursive_attach.c index 7248d0661ee9..6296bcf95481 100644 --- a/tools/testing/selftests/bpf/prog_tests/recursive_attach.c +++ b/tools/testing/selftests/bpf/prog_tests/recursive_attach.c @@ -67,3 +67,51 @@ void test_recursive_fentry_attach(void) fentry_recursive__destroy(tracing_chain[i]); } } + +/* + * Test that a tracing prog reattachment (when we land in + * "prog->aux->dst_trampoline and tgt_prog is NULL" branch in + * bpf_tracing_prog_attach) does not lead to a crash due to missing attach_btf + */ +void test_fentry_attach_btf_presence(void) +{ + struct fentry_recursive_target *target_skel = NULL; + struct fentry_recursive *tracing_skel = NULL; + struct bpf_program *prog; + int err, link_fd, tgt_prog_fd; + + target_skel = fentry_recursive_target__open_and_load(); + if (!ASSERT_OK_PTR(target_skel, "fentry_recursive_target__open_and_load")) + goto close_prog; + + tracing_skel = fentry_recursive__open(); + if (!ASSERT_OK_PTR(tracing_skel, "fentry_recursive__open")) + goto close_prog; + + prog = tracing_skel->progs.recursive_attach; + tgt_prog_fd = bpf_program__fd(target_skel->progs.fentry_target); + err = bpf_program__set_attach_target(prog, tgt_prog_fd, "fentry_target"); + if (!ASSERT_OK(err, "bpf_program__set_attach_target")) + goto close_prog; + + err = fentry_recursive__load(tracing_skel); + if (!ASSERT_OK(err, "fentry_recursive__load")) + goto close_prog; + + LIBBPF_OPTS(bpf_link_create_opts, link_opts); + + link_fd = bpf_link_create(bpf_program__fd(tracing_skel->progs.recursive_attach), + 0, BPF_TRACE_FENTRY, &link_opts); + if (!ASSERT_GE(link_fd, 0, "link_fd")) + goto close_prog; + + fentry_recursive__detach(tracing_skel); + + err = fentry_recursive__attach(tracing_skel); + if (!ASSERT_ERR(err, "fentry_recursive__attach")) + goto close_prog; + +close_prog: + fentry_recursive_target__destroy(target_skel); + fentry_recursive__destroy(tracing_skel); +} diff --git a/tools/testing/selftests/bpf/progs/fentry_recursive_target.c b/tools/testing/selftests/bpf/progs/fentry_recursive_target.c index b6fb8ebd598d..f812d2de0c3c 100644 --- a/tools/testing/selftests/bpf/progs/fentry_recursive_target.c +++ b/tools/testing/selftests/bpf/progs/fentry_recursive_target.c @@ -18,3 +18,14 @@ int BPF_PROG(test1, int a) test1_result = a == 1; return 0; } + +/* + * Dummy bpf prog for testing attach_btf presence when attaching an fentry + * program. + */ +SEC("raw_tp/sys_enter") +int BPF_PROG(fentry_target, struct pt_regs *regs, long id) +{ + test1_result = id == 1; + return 0; +} -- 2.41.0