serial: uartps: Do not allow use aliases >= MAX_UART_INSTANCES

Aliases >= MAX_UART_INSTANCES is no problem to find out and use but in
error path is necessary skip clearing bits in bitmap to ensure that only
bits in allocated bitmap are handled and nothing beyond that.
Without this patch when for example serial90 alias is used then in error
patch bit 90 is clear in 32bit wide bitmap.

Fixes: ae1cca3fa347 ("serial: uartps: Change uart ID port allocation")
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index dad18169527013cee58abb08355b4c97bafc65aa..d34f7b4668d0e2ca491a5ffa35af4f05e07eef73 100644 (file)
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -1676,7 +1676,8 @@ err_out_unregister_driver:
        uart_unregister_driver(cdns_uart_data->cdns_uart_driver);
 err_out_id:
        mutex_lock(&bitmap_lock);
-       clear_bit(cdns_uart_data->id, bitmap);
+       if (cdns_uart_data->id < MAX_UART_INSTANCES)
+               clear_bit(cdns_uart_data->id, bitmap);
        mutex_unlock(&bitmap_lock);
        return rc;
 }
@@ -1701,7 +1702,8 @@ static int cdns_uart_remove(struct platform_device *pdev)
        rc = uart_remove_one_port(cdns_uart_data->cdns_uart_driver, port);
        port->mapbase = 0;
        mutex_lock(&bitmap_lock);
-       clear_bit(cdns_uart_data->id, bitmap);
+       if (cdns_uart_data->id < MAX_UART_INSTANCES)
+               clear_bit(cdns_uart_data->id, bitmap);
        mutex_unlock(&bitmap_lock);
        clk_disable_unprepare(cdns_uart_data->uartclk);
        clk_disable_unprepare(cdns_uart_data->pclk);