diff --git a/bcmdhd/wifi_hal/common.cpp b/bcmdhd/wifi_hal/common.cpp
index 887b530..5a9d5ab 100755
--- a/bcmdhd/wifi_hal/common.cpp
+++ b/bcmdhd/wifi_hal/common.cpp
@@ -166,14 +166,11 @@
     pthread_mutex_unlock(&info->cb_lock);
 }
 
-void wifi_unregister_vendor_handler(wifi_handle handle, uint32_t id, int subcmd)
+void wifi_unregister_vendor_handler_without_lock(wifi_handle handle, uint32_t id, int subcmd)
 {
     hal_info *info = (hal_info *)handle;
 
-    pthread_mutex_lock(&info->cb_lock);
-
     for (int i = 0; i < info->num_event_cb; i++) {
-
         if (info->event_cb[i].nl_cmd == NL80211_CMD_VENDOR
                 && info->event_cb[i].vendor_id == id
                 && info->event_cb[i].vendor_subcmd == subcmd) {
@@ -185,10 +182,16 @@
             break;
         }
     }
-
-    pthread_mutex_unlock(&info->cb_lock);
 }
 
+void wifi_unregister_vendor_handler(wifi_handle handle, uint32_t id, int subcmd)
+{
+    hal_info *info = (hal_info *)handle;
+
+    pthread_mutex_lock(&info->cb_lock);
+    wifi_unregister_vendor_handler_without_lock(handle, id, subcmd);
+    pthread_mutex_unlock(&info->cb_lock);
+}
 
 wifi_error wifi_register_cmd(wifi_handle handle, int id, WifiCommand *cmd)
 {
diff --git a/bcmdhd/wifi_hal/common.h b/bcmdhd/wifi_hal/common.h
index d5bc971..9065802 100755
--- a/bcmdhd/wifi_hal/common.h
+++ b/bcmdhd/wifi_hal/common.h
@@ -424,6 +424,7 @@
             uint32_t id, int subcmd, nl_recvmsg_msg_cb_t func, void *arg);
 
 void wifi_unregister_handler(wifi_handle handle, int cmd);
+void wifi_unregister_vendor_handler_without_lock(wifi_handle handle, uint32_t id, int subcmd);
 void wifi_unregister_vendor_handler(wifi_handle handle, uint32_t id, int subcmd);
 
 wifi_error wifi_register_cmd(wifi_handle handle, int id, WifiCommand *cmd);
diff --git a/bcmdhd/wifi_hal/cpp_bindings.h b/bcmdhd/wifi_hal/cpp_bindings.h
index 456f31c..8b5600a 100755
--- a/bcmdhd/wifi_hal/cpp_bindings.h
+++ b/bcmdhd/wifi_hal/cpp_bindings.h
@@ -347,6 +347,10 @@
         return wifi_register_vendor_handler(wifiHandle(), id, subcmd, &event_handler, this);
     }
 
+    void unregisterVendorHandlerWithoutLock(uint32_t id, int subcmd) {
+        wifi_unregister_vendor_handler_without_lock(wifiHandle(), id, subcmd);
+    }
+
     void unregisterVendorHandler(uint32_t id, int subcmd) {
         wifi_unregister_vendor_handler(wifiHandle(), id, subcmd);
     }
diff --git a/bcmdhd/wifi_hal/wifi_hal.cpp b/bcmdhd/wifi_hal/wifi_hal.cpp
index d3ffe57..c83c482 100755
--- a/bcmdhd/wifi_hal/wifi_hal.cpp
+++ b/bcmdhd/wifi_hal/wifi_hal.cpp
@@ -1043,7 +1043,36 @@
         : WifiCommand("SetRSSIMonitorCommand", handle, id), mMax_rssi(max_rssi), mMin_rssi
         (min_rssi), mHandler(eh)
         {
+            ALOGI("SetRSSIMonitorCommand %p created", this);
         }
+
+   virtual ~SetRSSIMonitorCommand() {
+        /*
+         * Mostly, this call will be no effect. However, this could be valid
+         * when object destroy without calling unregisterVendorHandler().
+         * This is added to protect hal crash due to use-after-free.
+         */
+        ALOGI("Try to remove event handler if exist, vendor 0x%0x, subcmd 0x%x",
+            GOOGLE_OUI, GOOGLE_RSSI_MONITOR_EVENT);
+        unregisterVendorHandlerWithoutLock(GOOGLE_OUI, GOOGLE_RSSI_MONITOR_EVENT);
+        ALOGI("SetRSSIMonitorCommand %p destroyed", this);
+   }
+
+   virtual void addRef() {
+        int refs = __sync_add_and_fetch(&mRefs, 1);
+        ALOGI("addRef: WifiCommand %p has %d references", this, refs);
+   }
+
+   virtual void releaseRef() {
+        int refs = __sync_sub_and_fetch(&mRefs, 1);
+        if (refs == 0) {
+            ALOGI("releaseRef: WifiCommand %p has deleted", this);
+            delete this;
+        } else {
+            ALOGI("releaseRef: WifiCommand %p has %d references", this, refs);
+        }
+   }
+
    int createRequest(WifiRequest& request, int enable) {
         int result = request.create(GOOGLE_OUI, WIFI_SUBCMD_SET_RSSI_MONITOR);
         if (result < 0) {
@@ -1759,11 +1788,13 @@
     NULL_CHECK_RETURN(cmd, "memory allocation failure", WIFI_ERROR_OUT_OF_MEMORY);
     wifi_error result = wifi_register_cmd(handle, id, cmd);
     if (result != WIFI_SUCCESS) {
+        ALOGI("wifi_register_cmd() is failed %d", id);
         cmd->releaseRef();
         return result;
     }
     result = (wifi_error)cmd->start();
     if (result != WIFI_SUCCESS) {
+        ALOGI("start() is failed %d", id);
         wifi_unregister_cmd(handle, id);
         cmd->releaseRef();
         return result;