| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.10 54/81] tty/serial: atmel: fix race condition (TX+DMA) | Date | Thu, 6 Apr 2017 10:38:46 +0200 |
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4.10-stable review patch. If anyone has any objections, please let me know.
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From: Richard Genoud <richard.genoud@gmail.com>
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>
--- drivers/tty/serial/atmel_serial.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -1938,6 +1938,11 @@ static void atmel_flush_buffer(struct ua 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; } /*
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