From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF9CBC1975A for ; Tue, 17 Mar 2020 19:27:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C141020753 for ; Tue, 17 Mar 2020 19:27:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584473254; bh=ud+J2Q3qt391n3hECs5XRQezNhWR0pVtJrpZj8YXNWI=; h=Subject:To:From:Date:List-ID:From; b=zZ7yjce1IEo50G9I+o2sK9dGwsDdp4NnZvArO1YgeflLpB8m6Bvs16f9ecPAW65Hg E539oAtLInz15TM9XGze4P24W1Q5nBtcsXqYMYwncWASn/4TviNqVsqSojfHJDcQXP bgMZxOD8LjJYLTPGzqlB/7SBpoq0SFHvdQZ4IZqg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726452AbgCQT1e (ORCPT ); Tue, 17 Mar 2020 15:27:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:39364 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726294AbgCQT1e (ORCPT ); Tue, 17 Mar 2020 15:27:34 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 09E3120752; Tue, 17 Mar 2020 19:27:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584473253; bh=ud+J2Q3qt391n3hECs5XRQezNhWR0pVtJrpZj8YXNWI=; h=Subject:To:From:Date:From; b=eumqYbu6aw99cd3gNi1cWf/DGKk9JHBf8iMtiUYv9YKNP6irVKdDdNPOhipolHq3c x5H+tLsMf1/oeMmkwjXgSlbkh53XPAxnC1vXcN5QZW7qBUTVDL1iSr8EybLksivU+F vTXeoFcFj3nDhZSWGhpdITVhe2rRr3hoGLJ7uHp0= Subject: patch "USB: cdc-acm: fix rounding error in TIOCSSERIAL" added to usb-linus To: anthony.mallet@laas.fr, gregkh@linuxfoundation.org, stable@vger.kernel.org From: Date: Tue, 17 Mar 2020 20:27:23 +0100 Message-ID: <158447324315227@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled USB: cdc-acm: fix rounding error in TIOCSSERIAL to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will hopefully also be merged in Linus's tree for the next -rc kernel release. If you have any questions about this process, please let me know. >From b401f8c4f492cbf74f3f59c9141e5be3071071bb Mon Sep 17 00:00:00 2001 From: Anthony Mallet Date: Thu, 12 Mar 2020 14:31:01 +0100 Subject: USB: cdc-acm: fix rounding error in TIOCSSERIAL By default, tty_port_init() initializes those parameters to a multiple of HZ. For instance in line 69 of tty_port.c: port->close_delay = (50 * HZ) / 100; https://github.com/torvalds/linux/blob/master/drivers/tty/tty_port.c#L69 With e.g. CONFIG_HZ = 250 (as this is the case for Ubuntu 18.04 linux-image-4.15.0-37-generic), the default setting for close_delay is thus 125. When ioctl(fd, TIOCGSERIAL, &s) is executed, the setting returned in user space is '12' (125/10). When ioctl(fd, TIOCSSERIAL, &s) is then executed with the same setting '12', the value is interpreted as '120' which is different from the current setting and a EPERM error may be raised by set_serial_info() if !CAP_SYS_ADMIN. https://github.com/torvalds/linux/blob/master/drivers/usb/class/cdc-acm.c#L919 Fixes: ba2d8ce9db0a6 ("cdc-acm: implement TIOCSSERIAL to avoid blocking close(2)") Signed-off-by: Anthony Mallet Cc: stable Link: https://lore.kernel.org/r/20200312133101.7096-2-anthony.mallet@laas.fr Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-acm.c | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-) diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index da619176deca..47f09a6ce7bd 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -907,6 +907,7 @@ static int set_serial_info(struct tty_struct *tty, struct serial_struct *ss) { struct acm *acm = tty->driver_data; unsigned int closing_wait, close_delay; + unsigned int old_closing_wait, old_close_delay; int retval = 0; close_delay = msecs_to_jiffies(ss->close_delay * 10); @@ -914,18 +915,24 @@ static int set_serial_info(struct tty_struct *tty, struct serial_struct *ss) ASYNC_CLOSING_WAIT_NONE : msecs_to_jiffies(ss->closing_wait * 10); + /* we must redo the rounding here, so that the values match */ + old_close_delay = jiffies_to_msecs(acm->port.close_delay) / 10; + old_closing_wait = acm->port.closing_wait == ASYNC_CLOSING_WAIT_NONE ? + ASYNC_CLOSING_WAIT_NONE : + jiffies_to_msecs(acm->port.closing_wait) / 10; + mutex_lock(&acm->port.mutex); - if (!capable(CAP_SYS_ADMIN)) { - if ((close_delay != acm->port.close_delay) || - (closing_wait != acm->port.closing_wait)) + if ((ss->close_delay != old_close_delay) || + (ss->closing_wait != old_closing_wait)) { + if (!capable(CAP_SYS_ADMIN)) retval = -EPERM; - else - retval = -EOPNOTSUPP; - } else { - acm->port.close_delay = close_delay; - acm->port.closing_wait = closing_wait; - } + else { + acm->port.close_delay = close_delay; + acm->port.closing_wait = closing_wait; + } + } else + retval = -EOPNOTSUPP; mutex_unlock(&acm->port.mutex); return retval; -- 2.25.1