Merge branch 'cleanup the legacy probe_event on failed scenario'

Chuang Wang says:

====================
A potential scenario, when an error is returned after
add_uprobe_event_legacy() in perf_event_uprobe_open_legacy(), or
bpf_program__attach_perf_event_opts() in
bpf_program__attach_uprobe_opts() returns an error, the uprobe_event
that was previously created is not cleaned.

At the same time, the legacy kprobe_event also have similar problems.

With these patches, whenever an error is returned, it ensures that
the created kprobe_event/uprobe_event is cleaned.

V1 -> v3:

- add detail commits
- call remove_kprobe_event_legacy() on failed bpf_program__attach_perf_event_opts()

v3 -> v4:

- cleanup the legacy kprobe_event on failed add/attach_event
====================
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

tools/lib/bpf/libbpf.c

@@ -9877,10 +9877,11 @@ static int perf_event_kprobe_open_legacy(const char *probe_name, bool retprobe,
 	}
 	type = determine_kprobe_perf_type_legacy(probe_name, retprobe);
 	if (type < 0) {
+		err = type;
 		pr_warn("failed to determine legacy kprobe event id for '%s+0x%zx': %s\n",
 			kfunc_name, offset,
-			libbpf_strerror_r(type, errmsg, sizeof(errmsg)));
-		return type;
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		goto err_clean_legacy;
 	}
 	attr.size = sizeof(attr);
 	attr.config = type;
@@ -9894,9 +9895,14 @@ static int perf_event_kprobe_open_legacy(const char *probe_name, bool retprobe,
 		err = -errno;
 		pr_warn("legacy kprobe perf_event_open() failed: %s\n",
 			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
-		return err;
+		goto err_clean_legacy;
 	}
 	return pfd;
+
+err_clean_legacy:
+	/* Clear the newly added legacy kprobe_event */
+	remove_kprobe_event_legacy(probe_name, retprobe);
+	return err;
 }
 
 struct bpf_link *
@@ -9953,7 +9959,7 @@ bpf_program__attach_kprobe_opts(const struct bpf_program *prog,
 			prog->name, retprobe ? "kretprobe" : "kprobe",
 			func_name, offset,
 			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
-		goto err_out;
+		goto err_clean_legacy;
 	}
 	if (legacy) {
 		struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
@@ -9964,6 +9970,10 @@ bpf_program__attach_kprobe_opts(const struct bpf_program *prog,
 	}
 
 	return link;
+
+err_clean_legacy:
+	if (legacy)
+		remove_kprobe_event_legacy(legacy_probe, retprobe);
 err_out:
 	free(legacy_probe);
 	return libbpf_err_ptr(err);
@@ -10238,9 +10248,10 @@ static int perf_event_uprobe_open_legacy(const char *probe_name, bool retprobe,
 	}
 	type = determine_uprobe_perf_type_legacy(probe_name, retprobe);
 	if (type < 0) {
+		err = type;
 		pr_warn("failed to determine legacy uprobe event id for %s:0x%zx: %d\n",
 			binary_path, offset, err);
-		return type;
+		goto err_clean_legacy;
 	}
 
 	memset(&attr, 0, sizeof(attr));
@@ -10255,9 +10266,14 @@ static int perf_event_uprobe_open_legacy(const char *probe_name, bool retprobe,
 	if (pfd < 0) {
 		err = -errno;
 		pr_warn("legacy uprobe perf_event_open() failed: %d\n", err);
-		return err;
+		goto err_clean_legacy;
 	}
 	return pfd;
+
+err_clean_legacy:
+	/* Clear the newly added legacy uprobe_event */
+	remove_uprobe_event_legacy(probe_name, retprobe);
+	return err;
 }
 
 /* Return next ELF section of sh_type after scn, or first of that type if scn is NULL. */
@@ -10591,7 +10607,7 @@ bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
 			prog->name, retprobe ? "uretprobe" : "uprobe",
 			binary_path, func_offset,
 			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
-		goto err_out;
+		goto err_clean_legacy;
 	}
 	if (legacy) {
 		struct bpf_link_perf *perf_link = container_of(link, struct bpf_link_perf, link);
@@ -10601,10 +10617,13 @@ bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
 		perf_link->legacy_is_retprobe = retprobe;
 	}
 	return link;
+
+err_clean_legacy:
+	if (legacy)
+		remove_uprobe_event_legacy(legacy_probe, retprobe);
 err_out:
 	free(legacy_probe);
 	return libbpf_err_ptr(err);
-
 }
 
 /* Format of u[ret]probe section definition supporting auto-attach: