fix: guard mount info cache initialization failure

Prevent proc-events from accessing an uninitialized mount info bihash when
mount_info_cache_init() fails. Propagate the initialization error from
create_and_init_proc_info_caches() and add runtime guards before mount info
cache lookup/stat/root-check paths.

Author: yinjiping

agent/src/ebpf/user/mount.c

@@ -216,6 +216,9 @@ int mount_info_cache_init(const char *name)
 
 struct mount_info *mount_info_cache_lookup(pid_t pid, u64 mntns_id)
 {
+	if (!enable_mount_info_cache())
+		return MOUNT_INFO_INVAL;
+
 	if (mntns_id == 0 && pid > 0) {
 		if (get_mount_ns_id(pid, &mntns_id))
 			return MOUNT_INFO_INVAL;
@@ -552,6 +555,9 @@ static int check_mount_kvp_cb(mount_info_hash_kv * kvp, void *ctx)
 
 void collect_mount_info_stats(bool output_log)
 {
+	if (!enable_mount_info_cache())
+		return;
+
 	u64 elems_count = 0;
 	mount_info_hash_t *h = &mount_info_hash;
 	mount_info_hash_foreach_key_value_pair(h,
@@ -592,6 +598,9 @@ void check_and_cleanup_mount_info(pid_t pid, u64 mntns_id)
 // Periodically check whether the host node's mount information has changed.
 void check_root_mount_info(bool output_log)
 {
+	if (!enable_mount_info_cache())
+		return;
+
 	u32 new_hash = 0;
 	hash_mountinfo_file(1, &new_hash);
 	if (new_hash != 0 && new_hash != host_root_mountinfo_hash) {

agent/src/ebpf/user/proc.c

@@ -762,7 +762,10 @@ void *get_symbol_cache(pid_t pid, bool new_cache)
 int create_and_init_proc_info_caches(void)
 {
 	// Initialize the mount information cache.
-	mount_info_cache_init("mount-info-cache");
+	if (mount_info_cache_init("mount-info-cache")) {
+		ebpf_warning("mount_info_cache_init() failed.\n");
+		return ETR_NOMEM;
+	}
 
 	/*
 	 * Building a 'proc_event_ring' for handling process events.

agent/src/ebpf/user/socket.c

@@ -3094,7 +3094,8 @@ int running_socket_tracer(tracer_callback_t handle,
 	socket_tracer_set_probes(tps);
 	golang_trace_init();
 	openssl_trace_init();
-	create_and_init_proc_info_caches();
+	if ((ret = create_and_init_proc_info_caches()))
+		return ret;
 
 	struct bpf_tracer *tracer =
 	    setup_bpf_tracer(SK_TRACER_NAME, bpf_load_buffer_name,