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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68314C433F5 for ; Mon, 28 Feb 2022 07:58:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233312AbiB1H72 (ORCPT ); Mon, 28 Feb 2022 02:59:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59980 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233761AbiB1H71 (ORCPT ); Mon, 28 Feb 2022 02:59:27 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EE87746B26 for ; Sun, 27 Feb 2022 23:58:48 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 60CE6CE0B3C for ; Mon, 28 Feb 2022 07:58:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 554CAC340F1; Mon, 28 Feb 2022 07:58:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646035125; bh=UBrpUIZgMkgNinqElYQBgDAPvHk1rUe3FvwDtkjmowM=; h=Subject:To:Cc:From:Date:From; b=ipMrrRX9/pHpwmuZf24/4MhXtohgTquM/AIckXTiODhlXBEN+aX1LbOtIxcLec9d8 kk7+4CMrmv66qaTsLcaUQkWGWdFApsGibGzlTKfT8Bd/DVveyTVQXjlHjZAmTWeCZO czsR3fvO3XA9Sa/3UFXiFl2xjRKTpi3JS8Q/0x4o= Subject: FAILED: patch "[PATCH] tty: n_gsm: fix deadlock in gsmtty_open()" failed to apply to 4.19-stable tree To: daniel.starke@siemens.com, gregkh@linuxfoundation.org Cc: From: Date: Mon, 28 Feb 2022 08:58:35 +0100 Message-ID: <164603511525421@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.19-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 . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From a2ab75b8e76e455af7867e3835fd9cdf386b508f Mon Sep 17 00:00:00 2001 From: "daniel.starke@siemens.com" Date: Thu, 17 Feb 2022 23:31:23 -0800 Subject: [PATCH] tty: n_gsm: fix deadlock in gsmtty_open() In the current implementation the user may open a virtual tty which then could fail to establish the underlying DLCI. The function gsmtty_open() gets stuck in tty_port_block_til_ready() while waiting for a carrier rise. This happens if the remote side fails to acknowledge the link establishment request in time or completely. At some point gsm_dlci_close() is called to abort the link establishment attempt. The function tries to inform the associated virtual tty by performing a hangup. But the blocking loop within tty_port_block_til_ready() is not informed about this event. The patch proposed here fixes this by resetting the initialization state of the virtual tty to ensure the loop exits and triggering it to make tty_port_block_til_ready() return. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke Link: https://lore.kernel.org/r/20220218073123.2121-7-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 8ff5c0c61233..fa92f727fdf8 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1457,6 +1457,9 @@ static void gsm_dlci_close(struct gsm_dlci *dlci) if (dlci->addr != 0) { tty_port_tty_hangup(&dlci->port, false); kfifo_reset(&dlci->fifo); + /* Ensure that gsmtty_open() can return. */ + tty_port_set_initialized(&dlci->port, 0); + wake_up_interruptible(&dlci->port.open_wait); } else dlci->gsm->dead = true; /* Unregister gsmtty driver,report gsmtty dev remove uevent for user */