Pinned F3 HAL source evidence; no target execution. IRQ error branch can invoke RxISR before final errorcode snapshot. Application completion guard prevents rearming from clearing the pending ErrorCode.

void HAL_UART_IRQHandler(UART_HandleTypeDef *huart)
{
  uint32_t isrflags   = READ_REG(huart->Instance->ISR);
  uint32_t cr1its     = READ_REG(huart->Instance->CR1);
  uint32_t cr3its     = READ_REG(huart->Instance->CR3);

  uint32_t errorflags;
  uint32_t errorcode;

  /* If no error occurs */
  errorflags = (isrflags & (uint32_t)(USART_ISR_PE | USART_ISR_FE | USART_ISR_ORE | USART_ISR_NE | USART_ISR_RTOF));
  if (errorflags == 0U)
  {
    /* UART in mode Receiver ---------------------------------------------------*/
    if (((isrflags & USART_ISR_RXNE) != 0U)
        && ((cr1its & USART_CR1_RXNEIE) != 0U))
    {
      if (huart->RxISR != NULL)
      {
        huart->RxISR(huart);
      }
      return;
    }
  }

  /* If some errors occur */
  if ((errorflags != 0U)
      && (((cr3its & USART_CR3_EIE) != 0U)
          || ((cr1its & (USART_CR1_RXNEIE | USART_CR1_PEIE | USART_CR1_RTOIE)) != 0U)))
  {
    /* UART parity error interrupt occurred -------------------------------------*/
    if (((isrflags & USART_ISR_PE) != 0U) && ((cr1its & USART_CR1_PEIE) != 0U))
    {
      __HAL_UART_CLEAR_FLAG(huart, UART_CLEAR_PEF);

      huart->ErrorCode |= HAL_UART_ERROR_PE;
    }

    /* UART frame error interrupt occurred --------------------------------------*/
    if (((isrflags & USART_ISR_FE) != 0U) && ((cr3its & USART_CR3_EIE) != 0U))
    {
      __HAL_UART_CLEAR_FLAG(huart, UART_CLEAR_FEF);

      huart->ErrorCode |= HAL_UART_ERROR_FE;
    }

    /* UART noise error interrupt occurred --------------------------------------*/
    if (((isrflags & USART_ISR_NE) != 0U) && ((cr3its & USART_CR3_EIE) != 0U))
    {
      __HAL_UART_CLEAR_FLAG(huart, UART_CLEAR_NEF);

      huart->ErrorCode |= HAL_UART_ERROR_NE;
    }

    /* UART Over-Run interrupt occurred -----------------------------------------*/
    if (((isrflags & USART_ISR_ORE) != 0U)
        && (((cr1its & USART_CR1_RXNEIE) != 0U) ||
            ((cr3its & USART_CR3_EIE) != 0U)))
    {
      __HAL_UART_CLEAR_FLAG(huart, UART_CLEAR_OREF);

      huart->ErrorCode |= HAL_UART_ERROR_ORE;
    }

    /* UART Receiver Timeout interrupt occurred ---------------------------------*/
    if (((isrflags & USART_ISR_RTOF) != 0U) && ((cr1its & USART_CR1_RTOIE) != 0U))
    {
      __HAL_UART_CLEAR_FLAG(huart, UART_CLEAR_RTOF);

      huart->ErrorCode |= HAL_UART_ERROR_RTO;
    }

    /* Call UART Error Call back function if need be ----------------------------*/
    if (huart->ErrorCode != HAL_UART_ERROR_NONE)
    {
      /* UART in mode Receiver --------------------------------------------------*/
      if (((isrflags & USART_ISR_RXNE) != 0U)
          && ((cr1its & USART_CR1_RXNEIE) != 0U))
      {
        if (huart->RxISR != NULL)
        {
          huart->RxISR(huart);
        }
      }

      /* If Error is to be considered as blocking :
          - Receiver Timeout error in Reception
          - Overrun error in Reception
          - any error occurs in DMA mode reception
      */
      errorcode = huart->ErrorCode;
      if ((HAL_IS_BIT_SET(huart->Instance->CR3, USART_CR3_DMAR)) ||
          ((errorcode & (HAL_UART_ERROR_RTO | HAL_UART_ERROR_ORE)) != 0U))
      {
        /* Blocking error : transfer is aborted
           Set the UART state ready to be able to start again the process,
           Disable Rx Interrupts, and disable Rx DMA request, if ongoing */
        UART_EndRxTransfer(huart);

        /* Abort the UART DMA Rx channel if enabled */
        if (HAL_IS_BIT_SET(huart->Instance->CR3, USART_CR3_DMAR))
        {
          /* Disable the UART DMA Rx request if enabled */
          ATOMIC_CLEAR_BIT(huart->Instance->CR3, USART_CR3_DMAR);

          /* Abort the UART DMA Rx channel */
          if (huart->hdmarx != NULL)
          {
            /* Set the UART DMA Abort callback :
               will lead to call HAL_UART_ErrorCallback() at end of DMA abort procedure */
            huart->hdmarx->XferAbortCallback = UART_DMAAbortOnError;

            /* Abort DMA RX */
            if (HAL_DMA_Abort_IT(huart->hdmarx) != HAL_OK)
            {
              /* Call Directly huart->hdmarx->XferAbortCallback function in case of error */
              huart->hdmarx->XferAbortCallback(huart->hdmarx);
            }
          }
          else
          {
            /* Call user error callback */
#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)
            /*Call registered error callback*/
            huart->ErrorCallback(huart);
#else
            /*Call legacy weak error callback*/
            HAL_UART_ErrorCallback(huart);
#endif /* USE_HAL_UART_REGISTER_CALLBACKS */

          }
        }
        else
        {
          /* Call user error callback */
#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)
          /*Call registered error callback*/
          huart->ErrorCallback(huart);
#else
          /*Call legacy weak error callback*/
          HAL_UART_ErrorCallback(huart);
#endif /* USE_HAL_UART_REGISTER_CALLBACKS */
        }
      }
      else
      {
        /* Non Blocking error : transfer could go on.
           Error is notified to user through user error callback */
#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)
        /*Call registered error callback*/
        huart->ErrorCallback(huart);
#else
        /*Call legacy weak error callback*/
        HAL_UART_ErrorCallback(huart);
#endif /* USE_HAL_UART_REGISTER_CALLBACKS */
        huart->ErrorCode = HAL_UART_ERROR_NONE;
      }
    }
    return;

  } /* End if some error occurs */

  /* Check current reception Mode :
     If Reception till IDLE event has been selected : */
  if ((huart->ReceptionType == HAL_UART_RECEPTION_TOIDLE)
      && ((isrflags & USART_ISR_IDLE) != 0U)
      && ((cr1its & USART_ISR_IDLE) != 0U))
  {
    __HAL_UART_CLEAR_FLAG(huart, UART_CLEAR_IDLEF);

    /* Check if DMA mode is enabled in UART */
    if (HAL_IS_BIT_SET(huart->Instance->CR3, USART_CR3_DMAR))
    {
      /* DMA mode enabled */
      /* Check received length : If all expected data are received, do nothing,
         (DMA cplt callback will be called).
         Otherwise, if at least one data has already been received, IDLE event is to be notified to user */
      uint16_t nb_remaining_rx_data = (uint16_t) __HAL_DMA_GET_COUNTER(huart->hdmarx);
      if ((nb_remaining_rx_data > 0U)
          && (nb_remaining_rx_data < huart->RxXferSize))
      {
        /* Reception is not complete */
        huart->RxXferCount = nb_remaining_rx_data;

        /* In Normal mode, end DMA xfer and HAL UART Rx process*/
        if (huart->hdmarx->Init.Mode != DMA_CIRCULAR)
        {
          /* Disable PE and ERR (Frame error, noise error, overrun error) interrupts */
          ATOMIC_CLEAR_BIT(huart->Instance->CR1, USART_CR1_PEIE);
          ATOMIC_CLEAR_BIT(huart->Instance->CR3, USART_CR3_EIE);

          /* Disable the DMA transfer for the receiver request by resetting the DMAR bit
             in the UART CR3 register */
          ATOMIC_CLEAR_BIT(huart->Instance->CR3, USART_CR3_DMAR);

          /* At end of Rx process, restore huart->RxState to Ready */
          huart->RxState = HAL_UART_STATE_READY;
          huart->ReceptionType = HAL_UART_RECEPTION_STANDARD;

          ATOMIC_CLEAR_BIT(huart->Instance->CR1, USART_CR1_IDLEIE);

          /* Last bytes received, so no need as the abort is immediate */
          (void)HAL_DMA_Abort(huart->hdmarx);
        }

        /* Initialize type of RxEvent that correspond to RxEvent callback execution;
           In this case, Rx Event type is Idle Event */
        huart->RxEventType = HAL_UART_RXEVENT_IDLE;

#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)
        /*Call registered Rx Event callback*/
        huart->RxEventCallback(huart, (huart->RxXferSize - huart->RxXferCount));
#else
        /*Call legacy weak Rx Event callback*/
        HAL_UARTEx_RxEventCallback(huart, (huart->RxXferSize - huart->RxXferCount));
#endif /* (USE_HAL_UART_REGISTER_CALLBACKS) */
      }
      else
      {
        /* If DMA is in Circular mode, Idle event is to be reported to user
           even if occurring after a Transfer Complete event from DMA */
        if (nb_remaining_rx_data == huart->RxXferSize)
        {
          if (huart->hdmarx->Init.Mode == DMA_CIRCULAR)
          {
            /* Initialize type of RxEvent that correspond to RxEvent callback execution;
               In this case, Rx Event type is Idle Event */
            huart->RxEventType = HAL_UART_RXEVENT_IDLE;

#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)
            /*Call registered Rx Event callback*/
            huart->RxEventCallback(huart, huart->RxXferSize);
#else
            /*Call legacy weak Rx Event callback*/
            HAL_UARTEx_RxEventCallback(huart, huart->RxXferSize);
#endif /* (USE_HAL_UART_REGISTER_CALLBACKS) */
          }
        }
      }
      return;
    }
    else
    {
      /* DMA mode not enabled */
      /* Check received length : If all expected data are received, do nothing.
         Otherwise, if at least one data has already been received, IDLE event is to be notified to user */
      uint16_t nb_rx_data = huart->RxXferSize - huart->RxXferCount;
      if ((huart->RxXferCount > 0U)
          && (nb_rx_data > 0U))
      {
        /* Disable the UART Parity Error Interrupt and RXNE interrupts */
        ATOMIC_CLEAR_BIT(huart->Instance->CR1, (USART_CR1_RXNEIE | USART_CR1_PEIE));

        /* Disable the UART Error Interrupt: (Frame error, noise error, overrun error) */
        ATOMIC_CLEAR_BIT(huart->Instance->CR3, USART_CR3_EIE);

        /* Rx process is completed, restore huart->RxState to Ready */
        huart->RxState = HAL_UART_STATE_READY;
        huart->ReceptionType = HAL_UART_RECEPTION_STANDARD;

        /* Clear RxISR function pointer */
        huart->RxISR = NULL;

        ATOMIC_CLEAR_BIT(huart->Instance->CR1, USART_CR1_IDLEIE);

        /* Initialize type of RxEvent that correspond to RxEvent callback execution;
           In this case, Rx Event type is Idle Event */
        huart->RxEventType = HAL_UART_RXEVENT_IDLE;

#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)
        /*Call registered Rx complete callback*/
        huart->RxEventCallback(huart, nb_rx_data);
#else
        /*Call legacy weak Rx Event callback*/
        HAL_UARTEx_RxEventCallback(huart, nb_rx_data);
#endif /* (USE_HAL_UART_REGISTER_CALLBACKS) */
      }
      return;
    }
  }

  /* UART wakeup from Stop mode interrupt occurred ---------------------------*/
  if (((isrflags & USART_ISR_WUF) != 0U) && ((cr3its & USART_CR3_WUFIE) != 0U))
  {
    __HAL_UART_CLEAR_FLAG(huart, UART_CLEAR_WUF);

    /* UART Rx state is not reset as a reception process might be ongoing.
       If UART handle state fields need to be reset to READY, this could be done in Wakeup callback */

#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)
    /* Call registered Wakeup Callback */
    huart->WakeupCallback(huart);
#else
    /* Call legacy weak Wakeup Callback */
    HAL_UARTEx_WakeupCallback(huart);
#endif /* USE_HAL_UART_REGISTER_CALLBACKS */
    return;
  }

  /* UART in mode Transmitter ------------------------------------------------*/
  if (((isrflags & USART_ISR_TXE) != 0U)
      && ((cr1its & USART_CR1_TXEIE) != 0U))
  {
    if (huart->TxISR != NULL)
    {
      huart->TxISR(huart);
    }
    return;
  }

  /* UART in mode Transmitter (transmission end) -----------------------------*/
  if (((isrflags & USART_ISR_TC) != 0U) && ((cr1its & USART_CR1_TCIE) != 0U))
  {
    UART_EndTransmit_IT(huart);
    return;
  }

}

HAL_StatusTypeDef HAL_UART_Receive_IT(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size)
{
  /* Check that a Rx process is not already ongoing */
  if (huart->RxState == HAL_UART_STATE_READY)
  {
    if ((pData == NULL) || (Size == 0U))
    {
      return HAL_ERROR;
    }

    /* Set Reception type to Standard reception */
    huart->ReceptionType = HAL_UART_RECEPTION_STANDARD;

    /* Check that USART RTOEN bit is set */
    if (READ_BIT(huart->Instance->CR2, USART_CR2_RTOEN) != 0U)
    {
      /* Enable the UART Receiver Timeout Interrupt */
      ATOMIC_SET_BIT(huart->Instance->CR1, USART_CR1_RTOIE);
    }

    return (UART_Start_Receive_IT(huart, pData, Size));
  }
  else
  {
    return HAL_BUSY;
  }
}

HAL_StatusTypeDef HAL_UART_AbortReceive(UART_HandleTypeDef *huart)
{
  /* Disable RXNE, PE and ERR (Frame error, noise error, overrun error) interrupts */
  ATOMIC_CLEAR_BIT(huart->Instance->CR1, (USART_CR1_RXNEIE | USART_CR1_PEIE));
  ATOMIC_CLEAR_BIT(huart->Instance->CR3, USART_CR3_EIE);

  /* If Reception till IDLE event was ongoing, disable IDLEIE interrupt */
  if (huart->ReceptionType == HAL_UART_RECEPTION_TOIDLE)
  {
    ATOMIC_CLEAR_BIT(huart->Instance->CR1, (USART_CR1_IDLEIE));
  }

  /* Abort the UART DMA Rx channel if enabled */
  if (HAL_IS_BIT_SET(huart->Instance->CR3, USART_CR3_DMAR))
  {
    /* Disable the UART DMA Rx request if enabled */
    ATOMIC_CLEAR_BIT(huart->Instance->CR3, USART_CR3_DMAR);

    /* Abort the UART DMA Rx channel : use blocking DMA Abort API (no callback) */
    if (huart->hdmarx != NULL)
    {
      /* Set the UART DMA Abort callback to Null.
         No call back execution at end of DMA abort procedure */
      huart->hdmarx->XferAbortCallback = NULL;

      if (HAL_DMA_Abort(huart->hdmarx) != HAL_OK)
      {
        if (HAL_DMA_GetError(huart->hdmarx) == HAL_DMA_ERROR_TIMEOUT)
        {
          /* Set error code to DMA */
          huart->ErrorCode = HAL_UART_ERROR_DMA;

          return HAL_TIMEOUT;
        }
      }
    }
  }

  /* Clear the Error flags in the ICR register */
  __HAL_UART_CLEAR_FLAG(huart, UART_CLEAR_OREF | UART_CLEAR_NEF | UART_CLEAR_PEF | UART_CLEAR_FEF);

  /* Discard the received data */
  __HAL_UART_SEND_REQ(huart, UART_RXDATA_FLUSH_REQUEST);

  /* Restore huart->RxState to Ready */
  huart->RxState = HAL_UART_STATE_READY;
  huart->ReceptionType = HAL_UART_RECEPTION_STANDARD;

  return HAL_OK;
}

HAL_StatusTypeDef HAL_UARTEx_ReceiveToIdle_IT(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size)
{
  HAL_StatusTypeDef status = HAL_OK;

  /* Check that a Rx process is not already ongoing */
  if (huart->RxState == HAL_UART_STATE_READY)
  {
    if ((pData == NULL) || (Size == 0U))
    {
      return HAL_ERROR;
    }

    /* Set Reception type to reception till IDLE Event*/
    huart->ReceptionType = HAL_UART_RECEPTION_TOIDLE;
    huart->RxEventType = HAL_UART_RXEVENT_TC;

    (void)UART_Start_Receive_IT(huart, pData, Size);

    if (huart->ReceptionType == HAL_UART_RECEPTION_TOIDLE)
    {
      __HAL_UART_CLEAR_FLAG(huart, UART_CLEAR_IDLEF);
      ATOMIC_SET_BIT(huart->Instance->CR1, USART_CR1_IDLEIE);
    }
    else
    {
      /* In case of errors already pending when reception is started,
         Interrupts may have already been raised and lead to reception abortion.
         (Overrun error for instance).
         In such case Reception Type has been reset to HAL_UART_RECEPTION_STANDARD. */
      status = HAL_ERROR;
    }

    return status;
  }
  else
  {
    return HAL_BUSY;
  }
}