From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:46108 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S942062AbdDTGim (ORCPT ); Thu, 20 Apr 2017 02:38:42 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nicolas Ferre , Richard Genoud Subject: [PATCH 3.18 049/124] tty/serial: atmel: fix race condition (TX+DMA) Date: Thu, 20 Apr 2017 08:35:24 +0200 Message-Id: <20170420063558.939539472@linuxfoundation.org> In-Reply-To: <20170420063557.021306233@linuxfoundation.org> References: <20170420063557.021306233@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 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; } /*