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tty/serial: atmel: fix race condition (TX+DMA)

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commit 31ca2c63fdc0aee725cbd4f207c1256f5deaabde upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Richard Genoud 2017-03-20 11:52:41 +01:00 committed by Greg Kroah-Hartman
parent b3641939b1
commit e087ae68e8
1 changed files with 5 additions and 0 deletions
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5
drivers/tty/serial/atmel_serial.c
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@ -1938,6 +1938,11 @@ 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;
}
/*