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 9FE08C433EF for ; Wed, 4 May 2022 17:38:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356876AbiEDRma (ORCPT ); Wed, 4 May 2022 13:42:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35802 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356504AbiEDRJR (ORCPT ); Wed, 4 May 2022 13:09:17 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C8CAE4A3DB; Wed, 4 May 2022 09:55:09 -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 C2ACC617DE; Wed, 4 May 2022 16:55:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1D1D5C385A4; Wed, 4 May 2022 16:55:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1651683308; bh=/5CcQMipvtHUQTk/m1gHS7QbUj6IB812HRyP3TwC12U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0tf1kj0wsCguahC58TqBsOz1hqdSmbol9qLG0exxb7A/+j/EIV8Rv8/McLXv9Lyed hh43xetgXdl7Viu/zDVccy27/17r5jJkuSSQxmW1w8oXLUR/076j5bpTL6neS7XS7p t9lhqyPY1kvxLyXVikxs/KQt8dZ968MK8PjeznuA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Starke Subject: [PATCH 5.15 160/177] tty: n_gsm: fix wrong signal octet encoding in convergence layer type 2 Date: Wed, 4 May 2022 18:45:53 +0200 Message-Id: <20220504153107.801052455@linuxfoundation.org> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220504153053.873100034@linuxfoundation.org> References: <20220504153053.873100034@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Daniel Starke commit 06d5afd4d640eea67f5623e76cd5fc03359b7f3c upstream. 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 Link: https://lore.kernel.org/r/20220414094225.4527-5-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_gsm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -820,7 +820,7 @@ static int gsm_dlci_data_output(struct g 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);