]> git.karo-electronics.de Git - karo-tx-linux.git/commitdiff
tty/serial: atmel: fix race condition (TX+DMA)
authorRichard Genoud <richard.genoud@gmail.com>
Mon, 20 Mar 2017 10:52:41 +0000 (11:52 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 31 Mar 2017 15:26:19 +0000 (17:26 +0200)
If uart_flush_buffer() is called between atmel_tx_dma() and
atmel_complete_tx_dma(), the circular buffer has been cleared, but not
atmel_port->tx_len.
That leads to a circular buffer overflow (dumping (UART_XMIT_SIZE -
atmel_port->tx_len) bytes).

Tested-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
Cc: stable <stable@vger.kernel.org> # 3.12+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/tty/serial/atmel_serial.c

index dcebb28ffbc412d5282ef32b7f3c133ff984ab46..5f644515ed33be38032fd5127675256a8cf6762f 100644 (file)
@@ -1951,6 +1951,11 @@ static void atmel_flush_buffer(struct uart_port *port)
                atmel_uart_writel(port, ATMEL_PDC_TCR, 0);
                atmel_port->pdc_tx.ofs = 0;
        }
+       /*
+        * in uart_flush_buffer(), the xmit circular buffer has just
+        * been cleared, so we have to reset tx_len accordingly.
+        */
+       atmel_port->tx_len = 0;
 }
 
 /*