Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S943145AbdDTHqP (ORCPT ); Thu, 20 Apr 2017 03:46:15 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:35607 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S941414AbdDTHqL (ORCPT ); Thu, 20 Apr 2017 03:46:11 -0400 Subject: Re: [PATCH 3.18 049/124] tty/serial: atmel: fix race condition (TX+DMA) To: Greg Kroah-Hartman , linux-kernel@vger.kernel.org References: <20170420063557.021306233@linuxfoundation.org> <20170420063558.939539472@linuxfoundation.org> Cc: stable@vger.kernel.org, Nicolas Ferre From: Richard Genoud Message-ID: Date: Thu, 20 Apr 2017 09:46:03 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Icedove/45.6.0 MIME-Version: 1.0 In-Reply-To: <20170420063558.939539472@linuxfoundation.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2343 Lines: 75 On 20/04/2017 08:35, Greg Kroah-Hartman wrote: > 3.18-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Richard Genoud > > 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 > Signed-off-by: Richard Genoud > Signed-off-by: Greg Kroah-Hartman > > --- > 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 > @@ -1867,6 +1867,11 @@ static void atmel_flush_buffer(struct ua > 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 tx_len accordingly. > + */ > + atmel_port->tx_len = 0; > } > > /* > > Hi, This won't compile on 3.18 kernel since ->tx_len doesn't exist yet. Here is the backported version of this patch: Thanks ! ====================== 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 its length. That leads to a circular buffer overflow (dumping (UART_XMIT_SIZE - sg_dma_len(&atmel_port->sg_tx)) bytes). Signed-off-by: Richard Genoud --- drivers/tty/serial/atmel_serial.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index daaed7c79e4f..a10c778be2ad 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -1867,6 +1867,11 @@ 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; } /*