From patchwork Mon Feb 28 17:25:21 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 546989 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 33FD7C4332F for ; Mon, 28 Feb 2022 18:10:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232390AbiB1SLN (ORCPT ); Mon, 28 Feb 2022 13:11:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33644 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241506AbiB1SKB (ORCPT ); Mon, 28 Feb 2022 13:10:01 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 660FAB65E6; Mon, 28 Feb 2022 09:50:07 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 66FB160748; Mon, 28 Feb 2022 17:49:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7DA59C36AE7; Mon, 28 Feb 2022 17:49:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646070573; bh=Sufz76spNJVF7VI3y7kXmqzztncnszC5AqCLywGOenM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=m+ucDDs9c7UB/ZNW9rK38EhIu5BfyyOi+ywMu1Bc9vGOruYMUCZ9rU6sbkhMZ+1oP Iubzvu7bKWRfQkNF9S+bGZZgqVmd/ljPLkrVIDu9f8mz5wdakj2uG4ZfSiA9Om1Ik2 1/gyrJGet7p2yxx0kZB4UVqbvbUPn81gdTjoZ4b0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Starke Subject: [PATCH 5.16 159/164] tty: n_gsm: fix wrong modem processing in convergence layer type 2 Date: Mon, 28 Feb 2022 18:25:21 +0100 Message-Id: <20220228172414.101525266@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220228172359.567256961@linuxfoundation.org> References: <20220228172359.567256961@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@siemens.com commit 687f9ad43c52501f46164758e908a5dd181a87fc upstream. The function gsm_process_modem() exists to handle modem status bits of incoming frames. This includes incoming MSC (modem status command) frames and convergence layer type 2 data frames. The function, however, was only designed to handle MSC frames as it expects the command length. Within gsm_dlci_data() it is wrongly assumed that this is the same as the data frame length. This is only true if the data frame contains only 1 byte of payload. This patch names the length parameter of gsm_process_modem() in a generic manner to reflect its association. It also corrects all calls to the function to handle the variable number of modem status octets correctly in both cases. Fixes: 7263287af93d ("tty: n_gsm: Fixed logic to decode break signal from modem status") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke Link: https://lore.kernel.org/r/20220218073123.2121-6-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_gsm.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1021,25 +1021,25 @@ static void gsm_control_reply(struct gsm * @tty: virtual tty bound to the DLCI * @dlci: DLCI to affect * @modem: modem bits (full EA) - * @clen: command length + * @slen: number of signal octets * * Used when a modem control message or line state inline in adaption * layer 2 is processed. Sort out the local modem state and throttles */ static void gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci, - u32 modem, int clen) + u32 modem, int slen) { int mlines = 0; u8 brk = 0; int fc; - /* The modem status command can either contain one octet (v.24 signals) - or two octets (v.24 signals + break signals). The length field will - either be 2 or 3 respectively. This is specified in section - 5.4.6.3.7 of the 27.010 mux spec. */ + /* The modem status command can either contain one octet (V.24 signals) + * or two octets (V.24 signals + break signals). This is specified in + * section 5.4.6.3.7 of the 07.10 mux spec. + */ - if (clen == 2) + if (slen == 1) modem = modem & 0x7f; else { brk = modem & 0x7f; @@ -1096,6 +1096,7 @@ static void gsm_control_modem(struct gsm unsigned int brk = 0; struct gsm_dlci *dlci; int len = clen; + int slen; const u8 *dp = data; struct tty_struct *tty; @@ -1115,6 +1116,7 @@ static void gsm_control_modem(struct gsm return; dlci = gsm->dlci[addr]; + slen = len; while (gsm_read_ea(&modem, *dp++) == 0) { len--; if (len == 0) @@ -1131,7 +1133,7 @@ static void gsm_control_modem(struct gsm modem |= (brk & 0x7f); } tty = tty_port_tty_get(&dlci->port); - gsm_process_modem(tty, dlci, modem, clen); + gsm_process_modem(tty, dlci, modem, slen); if (tty) { tty_wakeup(tty); tty_kref_put(tty); @@ -1597,6 +1599,7 @@ static void gsm_dlci_data(struct gsm_dlc struct tty_struct *tty; unsigned int modem = 0; int len = clen; + int slen = 0; if (debug & 16) pr_debug("%d bytes for tty\n", len); @@ -1609,12 +1612,14 @@ static void gsm_dlci_data(struct gsm_dlc case 2: /* Asynchronous serial with line state in each frame */ while (gsm_read_ea(&modem, *data++) == 0) { len--; + slen++; if (len == 0) return; } + slen++; tty = tty_port_tty_get(port); if (tty) { - gsm_process_modem(tty, dlci, modem, clen); + gsm_process_modem(tty, dlci, modem, slen); tty_kref_put(tty); } fallthrough;