From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7705B37F322 for ; Mon, 5 Oct 2026 08:51:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791190293; cv=none; b=s5mQQExGKP7TpkyKhi73BKqzOnrP397TmR4mE1UcJelAWJFlDZEr6nwu4P0GvIKYLS589u5uvR6lK6X95/kk1BaKxeKBZbVPoRJ3z4TvfZWOSGGhWz59313NVlal/Hchk2FtOZ1GdZPTpXenaUhXJDS0vTesof+aBkiRLhUDrvk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791190293; c=relaxed/simple; bh=DW5KmrK+ydr8CeMPtnmPvdGptp55I0ZiABXbV7if0po=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=dWJkHnhdGCNV6d3yXLV2Okl+2QFFvYJy0xLqmOVn/5u3uXb+9P6hdaj778/ooVllwJTYXeu94mdjr5k6CHX0Dl0/O2zGWGUX9JRnpXJ7OdxZFi3fATZFgyTYpGRWOrBbsaKicPfO8vsvVfmmnuv1/7Gw2Mn7Upt6i7jny4xIcbI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=jQpwBI6L; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="jQpwBI6L" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CC6001F000FF; Mon, 5 Oct 2026 08:51:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1791190292; bh=yYbNDp7oni6yBSuTZu8NaOa8TuBNeMuDX05NhJu8Hes=; h=Subject:To:Cc:From:Date; b=jQpwBI6LccoJz//DFIEKQixFin4L+gxMgM5tUNiCMXjjNMxl/Stp3TrjAe+UrnMXk GTPIMrEfvXiBbSN8lWCUPveCZzm0ntK2yMkcTigrnFABJpQ9k8Yhw0Z8BgUfX9HhKc MpwexCVQUFd5Cwm4GUiQjgGebw6PZ8aP31zY7ta4= Subject: FAILED: patch "[PATCH] tty: abort break signalling on hangup" failed to apply to 5.15-stable tree To: johan@kernel.org,gregkh@linuxfoundation.org,stable@kernel.org Cc: From: Date: Mon, 05 Oct 2026 10:51:29 +0200 Message-ID: <2026100529-visitor-zoning-adb2@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 845a2737e0f5ffe5ca8d38de556012b0c9472cdd # git commit -s git send-email --to '' --in-reply-to '2026100529-visitor-zoning-adb2@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 845a2737e0f5ffe5ca8d38de556012b0c9472cdd Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Thu, 3 Sep 2026 18:37:36 +0200 Subject: [PATCH] tty: abort break signalling on hangup The break ioctls can race with hangup and end up calling into a tty driver for a device that is already gone or powered down. Drivers must handle this race, but TCSBRK and TCSBRKP should still be aborted to avoid calling back into the driver after a user-controlled timeout (possibly even after the tty has been reopened). Note that drivers should disable any break state on shutdown so just return on hangup (calling break_ctl() again is racy and will most likely fail for drivers handling the race). Fixes: f34d7a5b7010 ("tty: The big operations rework") Cc: stable Signed-off-by: Johan Hovold Link: https://patch.msgid.link/20260903163736.1499280-1-johan@kernel.org Signed-off-by: Greg Kroah-Hartman diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 48569035da56..1c30faae9ec1 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -620,6 +620,8 @@ static void __tty_hangup(struct tty_struct *tty, int exit_session) tty_ldisc_hangup(tty, cons_filp != NULL); + wake_up_interruptible(&tty->break_wait); + spin_lock_irq(&tty->ctrl.lock); clear_bit(TTY_THROTTLED, &tty->flags); clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); @@ -2431,6 +2433,7 @@ static int tiocgetd(struct tty_struct *tty, int __user *p) * send_break - performed time break * @tty: device to break on * @duration: timeout in mS + * @file: file object * * Perform a timed break on hardware that lacks its own driver level timed * break functionality. @@ -2438,8 +2441,9 @@ static int tiocgetd(struct tty_struct *tty, int __user *p) * Locking: * @tty->atomic_write_lock serializes */ -static int send_break(struct tty_struct *tty, unsigned int duration) +static int send_break(struct file *file, struct tty_struct *tty, unsigned int duration) { + long timeout; int retval; if (tty->ops->break_ctl == NULL) @@ -2453,13 +2457,26 @@ static int send_break(struct tty_struct *tty, unsigned int duration) return -EINTR; retval = tty->ops->break_ctl(tty, -1); - if (!retval) { - msleep_interruptible(duration); - retval = tty->ops->break_ctl(tty, 0); - } else if (retval == -EOPNOTSUPP) { - /* some drivers can tell only dynamically */ - retval = 0; + if (retval) { + if (retval == -EOPNOTSUPP) { + /* some drivers can tell only dynamically */ + retval = 0; + } + goto out_unlock; } + + timeout = msecs_to_jiffies(duration); + timeout = wait_event_interruptible_timeout(tty->break_wait, + tty_hung_up_p(file), + timeout); + /* return early on hangup only */ + if (timeout > 0) { + retval = -EIO; + goto out_unlock; + } + + retval = tty->ops->break_ctl(tty, 0); +out_unlock: tty_write_unlock(tty); if (signal_pending(current)) @@ -2727,10 +2744,10 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg) * This is used by the tcdrain() termios function. */ if (!arg) - return send_break(tty, 250); + return send_break(file, tty, 250); return 0; case TCSBRKP: /* support for POSIX tcsendbreak() */ - return send_break(tty, arg ? arg*100 : 250); + return send_break(file, tty, arg ? arg * 100 : 250); case TIOCMGET: return tty_tiocmget(tty, p); @@ -3090,6 +3107,7 @@ struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx) init_ldsem(&tty->ldisc_sem); init_waitqueue_head(&tty->write_wait); init_waitqueue_head(&tty->read_wait); + init_waitqueue_head(&tty->break_wait); INIT_WORK(&tty->hangup_work, do_tty_hangup); mutex_init(&tty->atomic_write_lock); spin_lock_init(&tty->ctrl.lock); diff --git a/include/linux/tty.h b/include/linux/tty.h index 0a46e4054dec..ad4e4a835f90 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -230,6 +230,7 @@ struct tty_struct { struct fasync_struct *fasync; wait_queue_head_t write_wait; wait_queue_head_t read_wait; + wait_queue_head_t break_wait; struct work_struct hangup_work; void *disc_data; void *driver_data;