From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753741AbdKHDF5 (ORCPT ); Tue, 7 Nov 2017 22:05:57 -0500 Received: from mail-pl0-f65.google.com ([209.85.160.65]:46576 "EHLO mail-pl0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750888AbdKHDFz (ORCPT ); Tue, 7 Nov 2017 22:05:55 -0500 X-Google-Smtp-Source: ABhQp+Q8MKFUAKlczCqsBu8M19Dtuyw7qupmt/z3SeYXgA+VI/6qOtlkc+7xAicTjKUNrifKix7tSw== From: "Ji-Ze Hong (Peter Hong)" X-Google-Original-From: "Ji-Ze Hong (Peter Hong)" To: gregkh@linuxfoundation.org Cc: jslaby@suse.com, lukas@wunner.de, rel+kernel@agilox.net, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, ricardo.ribalda@gmail.com, "Ji-Ze Hong (Peter Hong)" Subject: [PATCH V1 1/1] serial: 8250_fintek: Fix crash with baud rate B0 Date: Wed, 8 Nov 2017 11:05:46 +0800 Message-Id: <1510110346-28893-1-git-send-email-hpeter+linux_kernel@gmail.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The 8250_fintek.c is support the Fintek F81866/F81216 with dynamic clock. But It'll generate "division by zero" exception and crash in fintek_8250_set_termios() with baud rate 0 on baudrate_table[i] % baud. It can be tested with following C code: ... struct termios options; tcgetattr(fd, &options); ... options.c_cflag = CS8 | CREAD; /* baud rate 0 */ tcsetattr(fd, TCSANOW, &options); tcflush(fd, TCIOFLUSH); Fixes: 195638b6d44f ("serial: 8250_fintek: UART dynamic clocksource on Fintek F81866") Reported-by: Lukas Redlinger Cc: Lukas Redlinger Signed-off-by: Ji-Ze Hong (Peter Hong) --- drivers/tty/serial/8250/8250_fintek.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/8250/8250_fintek.c b/drivers/tty/serial/8250/8250_fintek.c index c41cbb52f1fe..3d66c2c0d7ee 100644 --- a/drivers/tty/serial/8250/8250_fintek.c +++ b/drivers/tty/serial/8250/8250_fintek.c @@ -312,6 +312,13 @@ void fintek_8250_set_termios(struct uart_port *port, struct ktermios *termios, F81866_UART_CLK_14_769MHZ, F81866_UART_CLK_18_432MHZ, F81866_UART_CLK_24MHZ }; + /* + * We'll use serial8250_do_set_termios() for baud = 0, otherwise It'll + * crash on baudrate_table[i] % baud with "division by zero". + */ + if (!baud) + goto exit; + switch (pdata->pid) { case CHIP_ID_F81216H: reg = RS485; @@ -324,8 +331,7 @@ void fintek_8250_set_termios(struct uart_port *port, struct ktermios *termios, dev_warn(port->dev, "%s: pid: %x Not support. use default set_termios.\n", __func__, pdata->pid); - serial8250_do_set_termios(port, termios, old); - return; + goto exit; } for (i = 0; i < ARRAY_SIZE(baudrate_table); ++i) { @@ -353,6 +359,7 @@ void fintek_8250_set_termios(struct uart_port *port, struct ktermios *termios, tty_termios_encode_baud_rate(termios, baud, baud); } +exit: serial8250_do_set_termios(port, termios, old); } -- 2.7.4