This is a note to let you know that I've just added the patch titled
tty/serial: atmel: fix race condition (TX+DMA)
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tty-serial-atmel-fix-race-condition-tx-dma.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 31ca2c63fdc0aee725cbd4f207c1256f5deaabde Mon Sep 17 00:00:00 2001
From: Richard Genoud <richard.genoud@xxxxxxxxx>
Date: Mon, 20 Mar 2017 11:52:41 +0100
Subject: tty/serial: atmel: fix race condition (TX+DMA)
From: Richard Genoud <richard.genoud@xxxxxxxxx>
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@xxxxxxxxxxxxx>
Signed-off-by: Richard Genoud <richard.genoud@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -1987,6 +1987,11 @@ 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;
}
/*
Patches currently in stable-queue which might be from richard.genoud@xxxxxxxxx are
queue-4.4/tty-serial-atmel-fix-race-condition-tx-dma.patch