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 86A67C433F5 for ; Mon, 2 May 2022 23:17:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229472AbiEBXU7 (ORCPT ); Mon, 2 May 2022 19:20:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37042 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229561AbiEBXU6 (ORCPT ); Mon, 2 May 2022 19:20:58 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3B71D31229 for ; Mon, 2 May 2022 16:17:27 -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 ams.source.kernel.org (Postfix) with ESMTPS id BFE40B81A65 for ; Mon, 2 May 2022 23:17:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 745EDC385AE; Mon, 2 May 2022 23:17:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1651533444; bh=vS6Tr9VSMYge8nEzN+4NCo9hZjq51D8nfrky3Xggk8M=; h=Subject:To:Cc:From:Date:From; b=2kWaTrgdjeH6iv/pO9++OPnlSD2aG3q4PIlxo3YWtdFtE7gZ3aiRlx11nKFI3MUWO Em+95ayaNAGRoNQxyWyg6+VKC/BZ9NMGLTUoY56Y0Hf8Kz2MZiNQqmvZ9fwleh5Vje M7sJxo8ONWuvXuQsJJF7s7hOe9gziQycfhaaR5bM= Subject: FAILED: patch "[PATCH] tty: n_gsm: fix frame reception handling" failed to apply to 5.4-stable tree To: daniel.starke@siemens.com, gregkh@linuxfoundation.org Cc: From: Date: Tue, 03 May 2022 01:17:23 +0200 Message-ID: <165153344337130@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 5.4-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 7a0e4b1733b635026a87c023f6d703faf0095e39 Mon Sep 17 00:00:00 2001 From: Daniel Starke Date: Thu, 14 Apr 2022 02:42:11 -0700 Subject: [PATCH] tty: n_gsm: fix frame reception handling The frame checksum (FCS) is currently handled in gsm_queue() after reception of a frame. However, this breaks layering. A workaround with 'received_fcs' was implemented so far. Furthermore, frames are handled as such even if no end flag was received. Move FCS calculation from gsm_queue() to gsm0_receive() and gsm1_receive(). Also delay gsm_queue() call there until a full frame was received to fix both points. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke Link: https://lore.kernel.org/r/20220414094225.4527-6-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 3ba2505908e3..4ce18b42c37a 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -219,7 +219,6 @@ struct gsm_mux { int encoding; u8 control; u8 fcs; - u8 received_fcs; u8 *txframe; /* TX framing buffer */ /* Method for the receiver side */ @@ -1794,18 +1793,7 @@ static void gsm_queue(struct gsm_mux *gsm) u8 cr; int address; int i, j, k, address_tmp; - /* We have to sneak a look at the packet body to do the FCS. - A somewhat layering violation in the spec */ - if ((gsm->control & ~PF) == UI) - gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf, gsm->len); - if (gsm->encoding == 0) { - /* WARNING: gsm->received_fcs is used for - gsm->encoding = 0 only. - In this case it contain the last piece of data - required to generate final CRC */ - gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->received_fcs); - } if (gsm->fcs != GOOD_FCS) { gsm->bad_fcs++; if (debug & 4) @@ -1993,19 +1981,25 @@ static void gsm0_receive(struct gsm_mux *gsm, unsigned char c) break; case GSM_DATA: /* Data */ gsm->buf[gsm->count++] = c; - if (gsm->count == gsm->len) + if (gsm->count == gsm->len) { + /* Calculate final FCS for UI frames over all data */ + if ((gsm->control & ~PF) != UIH) { + gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf, + gsm->count); + } gsm->state = GSM_FCS; + } break; case GSM_FCS: /* FCS follows the packet */ - gsm->received_fcs = c; - gsm_queue(gsm); + gsm->fcs = gsm_fcs_add(gsm->fcs, c); gsm->state = GSM_SSOF; break; case GSM_SSOF: - if (c == GSM0_SOF) { - gsm->state = GSM_SEARCH; - break; - } + gsm->state = GSM_SEARCH; + if (c == GSM0_SOF) + gsm_queue(gsm); + else + gsm->bad_size++; break; default: pr_debug("%s: unhandled state: %d\n", __func__, gsm->state); @@ -2024,11 +2018,24 @@ static void gsm0_receive(struct gsm_mux *gsm, unsigned char c) static void gsm1_receive(struct gsm_mux *gsm, unsigned char c) { if (c == GSM1_SOF) { - /* EOF is only valid in frame if we have got to the data state - and received at least one byte (the FCS) */ - if (gsm->state == GSM_DATA && gsm->count) { - /* Extract the FCS */ + /* EOF is only valid in frame if we have got to the data state */ + if (gsm->state == GSM_DATA) { + if (gsm->count < 1) { + /* Missing FSC */ + gsm->malformed++; + gsm->state = GSM_START; + return; + } + /* Remove the FCS from data */ gsm->count--; + if ((gsm->control & ~PF) != UIH) { + /* Calculate final FCS for UI frames over all + * data but FCS + */ + gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf, + gsm->count); + } + /* Add the FCS itself to test against GOOD_FCS */ gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->buf[gsm->count]); gsm->len = gsm->count; gsm_queue(gsm);