Commit 2655144f authored by Chuang Wang's avatar Chuang Wang Committed by Andrii Nakryiko
Browse files

libbpf: Cleanup the legacy uprobe_event on failed add/attach_event() 



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.

So, with this patch, when an error is returned, fix this by adding
remove_uprobe_event_legacy()

Signed-off-by: default avatarChuang Wang <nashuiliang@gmail.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220629151848.65587-4-nashuiliang@gmail.com
parent 5666fc99

tools/lib/bpf/libbpf.c

+14 −5
Original line number Diff line number Diff line
@@ -10248,9 +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, type);

		return type;

			binary_path, offset, err);

		goto err_clean_legacy;

	}



	memset(&attr, 0, sizeof(attr));
@@ -10265,9 +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. */
@@ -10601,7 +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);
@@ -10611,10 +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: