Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2994019AbbHHW1y (ORCPT ); Sat, 8 Aug 2015 18:27:54 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:36549 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2993560AbbHHWSK (ORCPT ); Sat, 8 Aug 2015 18:18:10 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Filipe Brandenburger , Peter Hurley Subject: [PATCH 4.1 097/123] n_tty: signal and flush atomically Date: Sat, 8 Aug 2015 15:09:35 -0700 Message-Id: <20150808220721.093210191@linuxfoundation.org> X-Mailer: git-send-email 2.5.0 In-Reply-To: <20150808220717.771230091@linuxfoundation.org> References: <20150808220717.771230091@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1981 Lines: 66 4.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Hurley commit 3b19e032295647b7be2aa3be62510db4aaeda759 upstream. When handling signalling char, claim the termios write lock before signalling waiting readers and writers to prevent further i/o before flushing the echo and output buffers. This prevents a userspace signal handler which may output from racing the terminal flush. Reference: Bugzilla #99351 ("Output truncated in ssh session after...") Fixes: commit d2b6f44779d3 ("n_tty: Fix signal handling flushes") Reported-by: Filipe Brandenburger Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_tty.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -1108,19 +1108,29 @@ static void eraser(unsigned char c, stru * Locking: ctrl_lock */ -static void isig(int sig, struct tty_struct *tty) +static void __isig(int sig, struct tty_struct *tty) { - struct n_tty_data *ldata = tty->disc_data; struct pid *tty_pgrp = tty_get_pgrp(tty); if (tty_pgrp) { kill_pgrp(tty_pgrp, sig, 1); put_pid(tty_pgrp); } +} + +static void isig(int sig, struct tty_struct *tty) +{ + struct n_tty_data *ldata = tty->disc_data; - if (!L_NOFLSH(tty)) { + if (L_NOFLSH(tty)) { + /* signal only */ + __isig(sig, tty); + + } else { /* signal and flush */ up_read(&tty->termios_rwsem); down_write(&tty->termios_rwsem); + __isig(sig, tty); + /* clear echo buffer */ mutex_lock(&ldata->output_lock); ldata->echo_head = ldata->echo_tail = 0; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/