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authorRichard Genoud <richard.genoud@gmail.com>2017-03-20 11:52:41 +0100
committerJiri Slaby <jslaby@suse.cz>2017-04-11 08:04:41 +0200
commit238b48d2187884a2852c7c8fe3ac9b5f86a86e4c (patch)
tree0fb711290028f12710ed50bd0e1922949cb601cc
parentf60473f8f623c42b917241f152e9fa248aa0261d (diff)
tty/serial: atmel: fix race condition (TX+DMA)
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> [rg] backport to 3.12 Signed-off-by: Richard Genoud <richard.genoud@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
-rw-r--r--drivers/tty/serial/atmel_serial.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index ab2e22bf54fd..04a809284d63 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -1690,6 +1690,11 @@ static void atmel_flush_buffer(struct uart_port *port)
UART_PUT_TCR(port, 0);
atmel_port->pdc_tx.ofs = 0;
}
+ /*
+ * in uart_flush_buffer(), the xmit circular buffer has just
+ * been cleared, so we have to reset its length accordingly.
+ */
+ sg_dma_len(&atmel_port->sg_tx) = 0;
}
/*