From patchwork Thu Apr 14 09:42:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "D. Starke" X-Patchwork-Id: 561411 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 F1C8DC433F5 for ; Thu, 14 Apr 2022 09:43:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241922AbiDNJqU (ORCPT ); Thu, 14 Apr 2022 05:46:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40790 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241900AbiDNJqP (ORCPT ); Thu, 14 Apr 2022 05:46:15 -0400 X-Greylist: delayed 62 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Thu, 14 Apr 2022 02:43:50 PDT Received: from mta-64-227.siemens.flowmailer.net (mta-64-227.siemens.flowmailer.net [185.136.64.227]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A01C570924 for ; Thu, 14 Apr 2022 02:43:50 -0700 (PDT) Received: by mta-64-227.siemens.flowmailer.net with ESMTPSA id 20220414094242f3bd7b303f1dd5c7c3 for ; Thu, 14 Apr 2022 11:42:47 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; s=fm1; d=siemens.com; i=daniel.starke@siemens.com; h=Date:From:Subject:To:Message-ID:MIME-Version:Content-Type:Content-Transfer-Encoding:Cc:References:In-Reply-To; bh=JjX0QExE5G0gdz7UMXnS8e0N4K1XjQpP52q6ISsyKsU=; b=YFV5IXw4YFUyNLztxoQnz4iwDHjU2ZZ7ie3Yvvn5YDEXtidCy8U1db6wpK47Kzd3mecqGe GLMIjIN03UMbs9aDhv3ztElAX7nYURG7S61RPancztV4uzuyo8HianLsTIAbwhMMzWQlCIOc 7yRp2aaB+nIUnJr6xLxtwdXEBGQvg=; From: "D. Starke" To: linux-serial@vger.kernel.org, gregkh@linuxfoundation.org, jirislaby@kernel.org Cc: linux-kernel@vger.kernel.org, Daniel Starke Subject: [PATCH 05/20] tty: n_gsm: fix wrong signal octet encoding in convergence layer type 2 Date: Thu, 14 Apr 2022 02:42:10 -0700 Message-Id: <20220414094225.4527-5-daniel.starke@siemens.com> In-Reply-To: <20220414094225.4527-1-daniel.starke@siemens.com> References: <20220414094225.4527-1-daniel.starke@siemens.com> MIME-Version: 1.0 X-Flowmailer-Platform: Siemens Feedback-ID: 519:519-314044:519-21489:flowmailer Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org From: Daniel Starke n_gsm is based on the 3GPP 07.010 and its newer version is the 3GPP 27.010. See https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=1516 The changes from 07.010 to 27.010 are non-functional. Therefore, I refer to the newer 27.010 here. Chapter 5.5.2 describes that the signal octet in convergence layer type 2 can be either one or two bytes. The length is encoded in the EA bit. This is set 1 for the last byte in the sequence. gsmtty_modem_update() handles this correctly but gsm_dlci_data_output() fails to set EA to 1. There is no case in which we encode two signal octets as there is no case in which we send out a break signal. Therefore, always set the EA bit to 1 for the signal octet to fix this. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke --- drivers/tty/n_gsm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index de97a3810731..3ba2505908e3 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -832,7 +832,7 @@ static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci) break; case 2: /* Unstructed with modem bits. Always one byte as we never send inline break data */ - *dp++ = gsm_encode_modem(dlci); + *dp++ = (gsm_encode_modem(dlci) << 1) | EA; break; } WARN_ON(kfifo_out_locked(&dlci->fifo, dp , len, &dlci->lock) != len);