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,URIBL_BLOCKED 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 673B3C433E0 for ; Wed, 27 May 2020 08:58:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 469702084C for ; Wed, 27 May 2020 08:58:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590569932; bh=7NsWjEVfjdhovKmRpMyEceBZU6SxnyQfAEPi10yf/FQ=; h=Subject:To:From:Date:List-ID:From; b=QlO3tpyfGYkhb311Xg3gWJh1L69Vc07jbUzXdzB0NO91c3X+5yaXuYGUl/76VC/Mx oRgsOHzSN2nBqKOs2jPPErnJubGqEoyb/E+w2Re8WKH4VZ9hc4rnJUBL8tfRZOsY3L 5GPbtlTylXa4YEgJRU/aV+BY+Salgtw5MzkoAEoU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728378AbgE0I6w (ORCPT ); Wed, 27 May 2020 04:58:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:34114 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728152AbgE0I6v (ORCPT ); Wed, 27 May 2020 04:58:51 -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 69BE12078B; Wed, 27 May 2020 08:58:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590569930; bh=7NsWjEVfjdhovKmRpMyEceBZU6SxnyQfAEPi10yf/FQ=; h=Subject:To:From:Date:From; b=fxwfHto5Q6RLo6kbURlozaeTd0Y/Hsd8di7VJk8E3OxPRQ+Yrvmmy/O6zDI/+J/j/ b+ZMUGNXQ3dFyKt/p+Lo6WMMH8bk/TWI4oDsmQWKXqCENKVIzf4x3QL7Rn22UhiXng mVyWa1skonOk5+IHMvRZ3xGKuYU2TOpdsFl76lq8= Subject: patch "tty: hvc_console, fix crashes on parallel open/close" added to tty-testing To: jslaby@suse.cz, gregkh@linuxfoundation.org, rananta@codeaurora.org, stable@vger.kernel.org From: Date: Wed, 27 May 2020 10:58:38 +0200 Message-ID: <1590569918240220@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 tty: hvc_console, fix crashes on parallel open/close to my tty git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git in the tty-testing 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 be merged to the tty-next branch sometime soon, after it passes testing, and the merge window is open. If you have any questions about this process, please let me know. >From 24eb2377f977fe06d84fca558f891f95bc28a449 Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Tue, 26 May 2020 16:56:32 +0200 Subject: tty: hvc_console, fix crashes on parallel open/close hvc_open sets tty->driver_data to NULL when open fails at some point. Typically, the failure happens in hp->ops->notifier_add(). If there is a racing process which tries to open such mangled tty, which was not closed yet, the process will crash in hvc_open as tty->driver_data is NULL. All this happens because close wants to know whether open failed or not. But ->open should not NULL this and other tty fields for ->close to be happy. ->open should call tty_port_set_initialized(true) and close should check by tty_port_initialized() instead. So do this properly in this driver. So this patch removes these from ->open: * tty_port_tty_set(&hp->port, NULL). This happens on last close. * tty->driver_data = NULL. Dtto. * tty_port_put(&hp->port). This happens in shutdown and until now, this must have been causing a reference underflow, if I am not missing something. Signed-off-by: Jiri Slaby Cc: stable Reported-and-tested-by: Raghavendra Link: https://lore.kernel.org/r/20200526145632.13879-1-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman --- drivers/tty/hvc/hvc_console.c | 23 ++++++++--------------- 1 file changed, 8 insertions(+), 15 deletions(-) diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c index 436cc51c92c3..cdcc64ea2554 100644 --- a/drivers/tty/hvc/hvc_console.c +++ b/drivers/tty/hvc/hvc_console.c @@ -371,15 +371,14 @@ static int hvc_open(struct tty_struct *tty, struct file * filp) * tty fields and return the kref reference. */ if (rc) { - tty_port_tty_set(&hp->port, NULL); - tty->driver_data = NULL; - tty_port_put(&hp->port); printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc); - } else + } else { /* We are ready... raise DTR/RTS */ if (C_BAUD(tty)) if (hp->ops->dtr_rts) hp->ops->dtr_rts(hp, 1); + tty_port_set_initialized(&hp->port, true); + } /* Force wakeup of the polling thread */ hvc_kick(); @@ -389,22 +388,12 @@ static int hvc_open(struct tty_struct *tty, struct file * filp) static void hvc_close(struct tty_struct *tty, struct file * filp) { - struct hvc_struct *hp; + struct hvc_struct *hp = tty->driver_data; unsigned long flags; if (tty_hung_up_p(filp)) return; - /* - * No driver_data means that this close was issued after a failed - * hvc_open by the tty layer's release_dev() function and we can just - * exit cleanly because the kref reference wasn't made. - */ - if (!tty->driver_data) - return; - - hp = tty->driver_data; - spin_lock_irqsave(&hp->port.lock, flags); if (--hp->port.count == 0) { @@ -412,6 +401,9 @@ static void hvc_close(struct tty_struct *tty, struct file * filp) /* We are done with the tty pointer now. */ tty_port_tty_set(&hp->port, NULL); + if (!tty_port_initialized(&hp->port)) + return; + if (C_HUPCL(tty)) if (hp->ops->dtr_rts) hp->ops->dtr_rts(hp, 0); @@ -428,6 +420,7 @@ static void hvc_close(struct tty_struct *tty, struct file * filp) * waking periodically to check chars_in_buffer(). */ tty_wait_until_sent(tty, HVC_CLOSE_WAIT); + tty_port_set_initialized(&hp->port, false); } else { if (hp->port.count < 0) printk(KERN_ERR "hvc_close %X: oops, count is %d\n", -- 2.26.2