From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:57617 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965828AbcIVRr1 (ORCPT ); Thu, 22 Sep 2016 13:47:27 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Mendez Salinas, Fernando" , Andy Shevchenko Subject: [PATCH 4.7 082/184] serial: 8250_mid: fix divide error bug if baud rate is 0 Date: Thu, 22 Sep 2016 19:40:16 +0200 Message-Id: <20160922174052.220282770@linuxfoundation.org> In-Reply-To: <20160922174048.653794923@linuxfoundation.org> References: <20160922174048.653794923@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.7-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andy Shevchenko commit 47b34d2ef266e2c283b514d65c8963c2ccd42474 upstream. Since the commit c1a67b48f6a5 ("serial: 8250_pci: replace switch-case by formula for Intel MID"), the 8250 driver crashes in the byt_set_termios() function with a divide error. This is caused by the fact that a baud rate of 0 (B0) is not handled properly. Fix it by falling back to B9600 in this case. Reported-by: "Mendez Salinas, Fernando" Fixes: c1a67b48f6a5 ("serial: 8250_pci: replace switch-case by formula for Intel MID") Signed-off-by: Andy Shevchenko Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_mid.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/tty/serial/8250/8250_mid.c +++ b/drivers/tty/serial/8250/8250_mid.c @@ -154,6 +154,9 @@ static void mid8250_set_termios(struct u unsigned long w = BIT(24) - 1; unsigned long mul, div; + /* Gracefully handle the B0 case: fall back to B9600 */ + fuart = fuart ? fuart : 9600 * 16; + if (mid->board->freq < fuart) { /* Find prescaler value that satisfies Fuart < Fref */ if (mid->board->freq > baud)