HAL Library CAN Bus interrupt sources and callback functions
You need this.
HAL_CAN_ActivateNotification(&amp;hcan1, CAN_IT_RX_FIFO0_OVERRUN);


I don't know, no idea what you want.

Because, CAL_FLAG_FF0 clears the job before Callback.
/* Receive FIFO 0 full interrupt management ********************************/

if ((interrupts &amp; CAN_IT_RX_FIFO0_FULL) != 0U)
{
   if ((rf0rflags &amp; CAN_RF0R_FULL0) != 0U)
   {
      /* Clear FIFO 0 full Flag */
      __HAL_CAN_CLEAR_FLAG(hcan, CAN_FLAG_FF0); &lt;--------------------------- this

      /* Receive FIFO 0 full Callback */
#if USE_HAL_CAN_REGISTER_CALLBACKS == 1
      /* Call registered callback*/
      hcan-&gt;RxFifo0FullCallback(hcan);
#else
      /* Call weak (surcharged) callback */
      HAL_CAN_RxFifo0FullCallback(hcan);     &lt;--------------------------------- Callback
#endif /* USE_HAL_CAN_REGISTER_CALLBACKS */
   }
}