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 A397B3F23A6; Tue, 13 Oct 2026 12:38:31 +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=1791895112; cv=none; b=dKUEtyuFg+XgKZrb5i/CV+miKb6C35PQ+4vpWvxLHQ4VF+byrMymkAPqMwN6KRs+p1OEn2EN5o7Xh+OfII7YnMISh4RLzk7vRFGXAx1qcg/rzzTN6vgpho6xOEEMU/xSk6meT0pV3kCZ6pu/kiweqS3G+Akr+NRKBfVWgZXODTQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791895112; c=relaxed/simple; bh=dgEvSnww9dH+7atvQ1w+U2b4naHWHgXLPhLkORgEG8g=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mqb1CjQoAGNzF9fVftZivgx++Bd83p82dDnOiw78eAtIfWmxC8FNx2TdB0n0xcwmTUTjksIrdarEfvGIss6XbBJ7fouqqyOtzdb/aEpfbPoSQorl//qZ+tIa1eAiU+CN1dVFUJLfAr7YLWi2QK2BDwcw0kTPHcLmr1KJKHNnWIE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=dYVE4Sat; 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="dYVE4Sat" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BD34B1F000FF; Tue, 13 Oct 2026 12:38:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1791895111; bh=s9lVdm6hsGMfQJViEJwpJ59N0XdtXlx7Wg++SGwzeEE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=dYVE4SatR6j/V26STIbGiKzrHtZkoUBvYx5rWKyPhCuuAXg5dXwfNKQLWkTk0uV7L VlKsOEyA3MFHD2kkMOq9uCfyztC2d27k/d5rRr8GCwHejz4LXEIjWTpltrRe8SzE6i 9BULWIFFiJzdmqic09S0Crf3xzZipq8OW+x4uYyw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Johan Hovold Subject: [PATCH 6.12 164/497] tty: abort break signalling on hangup Date: Tue, 13 Oct 2026 13:35:31 +0200 Message-ID: <20261013112911.781955110@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261013112907.864180619@linuxfoundation.org> References: <20261013112907.864180619@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Johan Hovold commit 845a2737e0f5ffe5ca8d38de556012b0c9472cdd upstream. 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 --- drivers/tty/tty_io.c | 36 +++++++++++++++++++++++++++--------- include/linux/tty.h | 1 + 2 files changed, 28 insertions(+), 9 deletions(-) --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -623,6 +623,8 @@ static void __tty_hangup(struct tty_stru 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); @@ -2468,6 +2470,7 @@ static int tiocgetd(struct tty_struct *t * 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. @@ -2475,8 +2478,9 @@ static int tiocgetd(struct tty_struct *t * 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) @@ -2490,13 +2494,26 @@ static int send_break(struct tty_struct 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)) @@ -2765,10 +2782,10 @@ long tty_ioctl(struct file *file, unsign * 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); @@ -3131,6 +3148,7 @@ struct tty_struct *alloc_tty_struct(stru 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); --- 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;