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 382C7C433F5 for ; Tue, 3 May 2022 13:37:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236265AbiECNl1 (ORCPT ); Tue, 3 May 2022 09:41:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58368 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234960AbiECNl0 (ORCPT ); Tue, 3 May 2022 09:41:26 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 597892613C for ; Tue, 3 May 2022 06:37:54 -0700 (PDT) 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 dfw.source.kernel.org (Postfix) with ESMTPS id EA0A761770 for ; Tue, 3 May 2022 13:37:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 35F68C385AE; Tue, 3 May 2022 13:37:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1651585073; bh=S/KFN2ayiXw2lSbzwOg/h6rSDRPq0CF5xzzPN7cO0YE=; h=Subject:To:Cc:From:Date:From; b=PEP+sDsM5lFtYizInO/hs1Gr1UygrGsRlKQKTlHiTx6N3zCQcOv4E8EGPXaXLP+Uy gmfMkxI6Qb1W5I8H7UDIicxExpptQ1cyNed+W9mqcSng4P3lppbStHbkkemcgmOOlK vLenqhX1/evUNCd6+K/nlm2OXD4FEbYtcHolExCQ= Subject: FAILED: patch "[PATCH] tty: n_gsm: fix reset fifo race condition" failed to apply to 4.19-stable tree To: daniel.starke@siemens.com, gregkh@linuxfoundation.org Cc: From: Date: Tue, 03 May 2022 15:37:51 +0200 Message-ID: <165158507184211@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 73029a4d7161f8b6c0934553145ef574d2d0c645 Mon Sep 17 00:00:00 2001 From: Daniel Starke Date: Thu, 14 Apr 2022 02:42:22 -0700 Subject: [PATCH] tty: n_gsm: fix reset fifo race condition gsmtty_write() and gsm_dlci_data_output() properly guard the fifo access. However, gsm_dlci_close() and gsmtty_flush_buffer() modifies the fifo but do not guard this. Add a guard here to prevent race conditions on parallel writes to the fifo. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke Link: https://lore.kernel.org/r/20220414094225.4527-17-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 f3fb66be8513..15be4a235783 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1442,13 +1442,17 @@ static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control) static void gsm_dlci_close(struct gsm_dlci *dlci) { + unsigned long flags; + del_timer(&dlci->t1); if (debug & 8) pr_debug("DLCI %d goes closed.\n", dlci->addr); dlci->state = DLCI_CLOSED; if (dlci->addr != 0) { tty_port_tty_hangup(&dlci->port, false); + spin_lock_irqsave(&dlci->lock, flags); kfifo_reset(&dlci->fifo); + spin_unlock_irqrestore(&dlci->lock, flags); /* Ensure that gsmtty_open() can return. */ tty_port_set_initialized(&dlci->port, 0); wake_up_interruptible(&dlci->port.open_wait); @@ -3148,13 +3152,17 @@ static unsigned int gsmtty_chars_in_buffer(struct tty_struct *tty) static void gsmtty_flush_buffer(struct tty_struct *tty) { struct gsm_dlci *dlci = tty->driver_data; + unsigned long flags; + if (dlci->state == DLCI_CLOSED) return; /* Caution needed: If we implement reliable transport classes then the data being transmitted can't simply be junked once it has first hit the stack. Until then we can just blow it away */ + spin_lock_irqsave(&dlci->lock, flags); kfifo_reset(&dlci->fifo); + spin_unlock_irqrestore(&dlci->lock, flags); /* Need to unhook this DLCI from the transmit queue logic */ }