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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 79D10C282D7 for ; Sat, 2 Feb 2019 12:15:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 51E452086C for ; Sat, 2 Feb 2019 12:15:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727449AbfBBMPT convert rfc822-to-8bit (ORCPT ); Sat, 2 Feb 2019 07:15:19 -0500 Received: from coyote.holtmann.net ([212.227.132.17]:43091 "EHLO mail.holtmann.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727199AbfBBMPT (ORCPT ); Sat, 2 Feb 2019 07:15:19 -0500 Received: from marcel-macpro.fritz.box (p4FF9FD60.dip0.t-ipconnect.de [79.249.253.96]) by mail.holtmann.org (Postfix) with ESMTPSA id A8327CEF9A; Sat, 2 Feb 2019 13:23:06 +0100 (CET) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 12.2 \(3445.102.3\)) Subject: Re: [PATCH v2] Bluetooth: hci_uart: Switch pty driver to slave side in tty_set_termios() From: Marcel Holtmann In-Reply-To: <20190202072816.GA15630@myunghoj-Precision-5530> Date: Sat, 2 Feb 2019 13:15:16 +0100 Cc: Johan Hedberg , linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8BIT Message-Id: <3EC8C1C2-27AE-46B7-A345-860A87B94E6B@holtmann.org> References: <20190202072816.GA15630@myunghoj-Precision-5530> To: Myungho Jung X-Mailer: Apple Mail (2.3445.102.3) Sender: linux-bluetooth-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org Hi Myungho, > tty_set_termios() should be called with slave side of pty driver. So, If > tty driver is pty master, it needs to be switched to ->link. > > Reported-by: syzbot+a950165cbb86bdd023a4@syzkaller.appspotmail.com > Signed-off-by: Myungho Jung > --- > drivers/bluetooth/hci_ldisc.c | 27 ++++++++++++++++++++++----- > 1 file changed, 22 insertions(+), 5 deletions(-) > > diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c > index fbf7b4df23ab..0f6e70ea1dc3 100644 > --- a/drivers/bluetooth/hci_ldisc.c > +++ b/drivers/bluetooth/hci_ldisc.c > @@ -299,10 +299,21 @@ static int hci_uart_send_frame(struct hci_dev *hdev, struct sk_buff *skb) > return 0; > } > > +/* If pty master, return slave side */ > +static struct tty_struct *hci_uart_get_real_tty(struct tty_struct *tty) > +{ > + if (tty->driver->type == TTY_DRIVER_TYPE_PTY && > + tty->driver->subtype == PTY_TYPE_MASTER) > + tty->link; > + > + return tty; > +} > + > /* Flow control or un-flow control the device */ > void hci_uart_set_flow_control(struct hci_uart *hu, bool enable) > { > struct tty_struct *tty = hu->tty; > + struct tty_struct *real_tty; > struct ktermios ktermios; > int status; > unsigned int set = 0; > @@ -314,11 +325,14 @@ void hci_uart_set_flow_control(struct hci_uart *hu, bool enable) > return; > } > > + /* termios should be set from slave side if tty driver is pty */ > + real_tty = hci_uart_get_real_tty(tty); > + > if (enable) { > /* Disable hardware flow control */ > - ktermios = tty->termios; > + ktermios = real_tty->termios; > ktermios.c_cflag &= ~CRTSCTS; > - status = tty_set_termios(tty, &ktermios); > + status = tty_set_termios(real_tty, &ktermios); > BT_DBG("Disabling hardware flow control: %s", > status ? "failed" : "success"); > > @@ -350,9 +364,9 @@ void hci_uart_set_flow_control(struct hci_uart *hu, bool enable) > BT_DBG("Setting RTS: %s", status ? "failed" : "success"); > > /* Re-enable hardware flow control */ > - ktermios = tty->termios; > + ktermios = real_tty->termios; > ktermios.c_cflag |= CRTSCTS; > - status = tty_set_termios(tty, &ktermios); > + status = tty_set_termios(real_tty, &ktermios); > BT_DBG("Enabling hardware flow control: %s", > status ? "failed" : "success"); > } > @@ -367,9 +381,12 @@ void hci_uart_set_speeds(struct hci_uart *hu, unsigned int init_speed, > > void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed) > { > - struct tty_struct *tty = hu->tty; > + struct tty_struct *tty; > struct ktermios ktermios; > > + /* termios should be set from slave side if tty driver is pty */ > + tty = hci_uart_get_real_tty(hu->tty); > + didn’t we conclude that allowing the HCI line discipline on a PTY master isn't worth the effort? The ptm_unix98_ops doesn’t have the .set_termios and thus, just check that ops->set_termios is present in hci_uart_tty_open and if not fail with EOPNOTSUPP like we do for missing ops->write. Regards Marcel