From patchwork Wed May 4 16:45:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 569821 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 B72EAC433F5 for ; Wed, 4 May 2022 16:59:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354577AbiEDRDX (ORCPT ); Wed, 4 May 2022 13:03:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38034 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354488AbiEDRCF (ORCPT ); Wed, 4 May 2022 13:02:05 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DE4C94CD68; Wed, 4 May 2022 09:52:24 -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 7A234617C3; Wed, 4 May 2022 16:52:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C5655C385A4; Wed, 4 May 2022 16:52:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1651683138; bh=oLZiBmzCCSAKWuBDvcY+Z3V8jNlCc60+HGkO6tQErks=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=o+Jq2XcdGhgexqwkSzgF22PMHT+xTqn4z5R2RiFgBNJO+iixoqFNyWrtmvVImhn4x KeZ0kD78AS95Xnf58xRJaGmx0VtB78WdqnNrQD0cYUfXAUK+iYYV4Dwg6kmGF82wXl yal9+XSEGmtgBw8pXK+uSucyrOhGgjIb2xAHcWAQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Starke Subject: [PATCH 5.10 126/129] tty: n_gsm: fix reset fifo race condition Date: Wed, 4 May 2022 18:45:18 +0200 Message-Id: <20220504153031.563728783@linuxfoundation.org> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220504153021.299025455@linuxfoundation.org> References: <20220504153021.299025455@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Daniel Starke commit 73029a4d7161f8b6c0934553145ef574d2d0c645 upstream. 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 --- drivers/tty/n_gsm.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1422,13 +1422,17 @@ static int gsm_control_wait(struct gsm_m 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); @@ -3078,13 +3082,17 @@ static int gsmtty_chars_in_buffer(struct 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 */ }