clusterer: fix crash after MI reload

The crash was caused by accessing a dangling pointer to the capability
structure after it was freed.

Thanks to Suchi Sahoo from Five9 for reporting!

(cherry picked from commit cb8d631)

modules/clusterer/clusterer.c

@@ -1795,6 +1795,9 @@ int preserve_reg_caps(cluster_info_t *new_info)
 					LM_ERR("Failed to duplicate capabilities info\n");
 					return -1;
 				}
+
+				update_shtags_sync_status_cap(cl->cluster_id,
+					new_cl->capabilities);
 			}
 
 	return 0;

modules/clusterer/sharing_tags.c

@@ -596,6 +596,29 @@ int shtag_set_sync_status(str *tag_name, int cluster_id, str *capability,
 	return 0;
 }
 
+void update_shtags_sync_status_cap(int cluster_id, struct local_cap *new_caps)
+{
+	struct sharing_tag *tag;
+	struct shtag_sync_status *status;
+	struct local_cap *cap;
+
+	lock_start_write(shtags_lock);
+
+	for (tag = *shtags_list; tag; tag = tag->next) {
+		if (tag->cluster_id != cluster_id)
+			continue;
+
+		for (status=tag->sync_status; status; status=status->next)
+			for (cap = new_caps; cap; cap = cap->next)
+				if (!str_strcmp(&cap->reg.name, &status->capability->reg.name)) {
+					status->capability = cap;
+					break;
+				}
+	}
+
+	lock_stop_write(shtags_lock);
+}
+
 int shtag_sync_all_backup(int cluster_id, str *capability)
 {
 	struct sharing_tag *tag;

modules/clusterer/sharing_tags.h

@@ -70,6 +70,8 @@ int shtag_set_sync_status(str *tag_name, int cluster_id, str *capability,
 
 int shtag_sync_all_backup(int cluster_id, str *capability);
 
+void update_shtags_sync_status_cap(int cluster_id, struct local_cap *new_caps);
+
 /* script vars related functions */
 int var_get_sh_tag(struct sip_msg *msg,  pv_param_t *param, pv_value_t *res);