From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762305AbZE2SfL (ORCPT ); Fri, 29 May 2009 14:35:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756895AbZE2Seh (ORCPT ); Fri, 29 May 2009 14:34:37 -0400 Received: from mail.windriver.com ([147.11.1.11]:64750 "EHLO mail.wrs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759442AbZE2Seg (ORCPT ); Fri, 29 May 2009 14:34:36 -0400 From: Jason Wessel To: greg@kroah.com Cc: linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, Jason Wessel Subject: [PATCH 2/2] usb_serial: only allow sysrq on a console port Date: Fri, 29 May 2009 13:34:17 -0500 Message-Id: <1243622057-17671-3-git-send-email-jason.wessel@windriver.com> X-Mailer: git-send-email 1.6.3.1.9.g95405b In-Reply-To: <1243622057-17671-2-git-send-email-jason.wessel@windriver.com> References: <1243622057-17671-1-git-send-email-jason.wessel@windriver.com> <1243622057-17671-2-git-send-email-jason.wessel@windriver.com> X-OriginalArrivalTime: 29 May 2009 18:36:25.0562 (UTC) FILETIME=[5F4BDBA0:01C9E08C] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The only time a sysrq should get processed is if the attached device is a console. This is intended to protect sysrq execution on a host connected with a terminal program. Here is the problem scenario: host A <-- rs232 link --> host B Host A is using mincom and a usb pl2303 device to connect to host b which is a linux system with a usb pl2303 device acting as the serial console. When host B is rebooted the pl2303 emits random junk characters on reset. These character sequences contain serial break signals most of the time and when translated to a sysrq have caused host A to get random processes killed, reboots or power down. It is true that in this setup with this patch host B might still have the same problem as host A if you reboot host A. In most cases host A is a development host which seldom gets rebooted, and you could turn off sysrq temporarily on host B if you need to reboot host A. Signed-off-by: Jason Wessel --- drivers/usb/serial/generic.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c index df56ed3..4797402 100644 --- a/drivers/usb/serial/generic.c +++ b/drivers/usb/serial/generic.c @@ -529,7 +529,7 @@ void usb_serial_generic_unthrottle(struct tty_struct *tty) int usb_serial_handle_sysrq_char(struct usb_serial_port *port, unsigned int ch) { - if (port->sysrq) { + if (port->sysrq && port->console) { if (ch && time_before(jiffies, port->sysrq)) { handle_sysrq(ch, tty_port_tty_get(&port->port)); port->sysrq = 0; -- 1.6.3.1.9.g95405b