linux-kernel - [PATCH bpf-next] libbpf: Fix event name too long error

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Message-Id: <20250410052712.206785-1-yangfeng59949@163.com>
Date: Thu, 10 Apr 2025 13:27:12 +0800
From: Feng Yang <yangfeng59949@....com>
To: ast@...nel.org,
	daniel@...earbox.net,
	andrii@...nel.org,
	martin.lau@...ux.dev,
	eddyz87@...il.com,
	song@...nel.org,
	yonghong.song@...ux.dev,
	john.fastabend@...il.com,
	kpsingh@...nel.org,
	sdf@...ichev.me,
	haoluo@...gle.com,
	jolsa@...nel.org
Cc: bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH bpf-next] libbpf: Fix event name too long error

From: Feng Yang <yangfeng@...inos.cn>

If the event name is too long, it will cause an EINVAL error.

The kernel error path is
probes_write
    trace_parse_run_command
        create_or_delete_trace_uprobe
            trace_uprobe_create
                trace_probe_create
                    __trace_uprobe_create
                        traceprobe_parse_event_name
                            else if (len >= MAX_EVENT_NAME_LEN)
Requires less than 64 bytes.

Signed-off-by: Feng Yang <yangfeng@...inos.cn>
---
 tools/lib/bpf/libbpf.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index b2591f5cab65..8e48ba99f06c 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -12227,6 +12227,16 @@ bpf_program__attach_uprobe_multi(const struct bpf_program *prog,
 	return libbpf_err_ptr(err);
 }
 
+static const char *get_last_part(const char *path)
+{
+	const char *last_slash = strrchr(path, '/');
+
+	if (last_slash != NULL)
+		return last_slash + 1;
+	else
+		return path;
+}
+
 LIBBPF_API struct bpf_link *
 bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
 				const char *binary_path, size_t func_offset,
@@ -12241,7 +12251,7 @@ bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
 	size_t ref_ctr_off;
 	int pfd, err;
 	bool retprobe, legacy;
-	const char *func_name;
+	const char *func_name, *binary_name;
 
 	if (!OPTS_VALID(opts, bpf_uprobe_opts))
 		return libbpf_err_ptr(-EINVAL);
@@ -12254,6 +12264,7 @@ bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
 	if (!binary_path)
 		return libbpf_err_ptr(-EINVAL);
 
+	binary_name = get_last_part(binary_path);
 	/* Check if "binary_path" refers to an archive. */
 	archive_sep = strstr(binary_path, "!/");
 	if (archive_sep) {
@@ -12318,7 +12329,7 @@ bpf_program__attach_uprobe_opts(const struct bpf_program *prog, pid_t pid,
 			return libbpf_err_ptr(-EINVAL);
 
 		gen_uprobe_legacy_event_name(probe_name, sizeof(probe_name),
-					     binary_path, func_offset);
+					     binary_name, func_offset);
 
 		legacy_probe = strdup(probe_name);
 		if (!legacy_probe)
-- 
2.43.0