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 A73B1C433F5 for ; Mon, 9 May 2022 10:47:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230072AbiEIKvb (ORCPT ); Mon, 9 May 2022 06:51:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55778 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231358AbiEIKu6 (ORCPT ); Mon, 9 May 2022 06:50:58 -0400 Received: from mail-wm1-x32d.google.com (mail-wm1-x32d.google.com [IPv6:2a00:1450:4864:20::32d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1D3CF2D2E0B; Mon, 9 May 2022 03:46:36 -0700 (PDT) Received: by mail-wm1-x32d.google.com with SMTP id k126-20020a1ca184000000b003943fd07180so8011117wme.3; Mon, 09 May 2022 03:46:36 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=T3V/lJ4KUDk6qXJayPf/9nDf9cdeXl1HqcM89tsaVpI=; b=c3u+pHWHX+KRBICJluZBGRYy4OlWzlKvluuGrCdgoXGH0a69jGDaP0k5BX/dgB7oYw rfmI/FphL878Amre2FtUZy7e0fOUddHib2whV4Cx8oS2gwvzDLnAmID7U01ziYkBBV8y jBS9h9uqboJuFR3YJ4hVnruqamNMgQ3HUe3HyqcefpqL+uyWDpcEsFYDJkB1+bSFU2cY yRggGixlIfKFY1K5dMk3Dm2nkwcj2zfbFqgnUtA2h6FR5Zrt7Hs1NYmxYjz/Iftc6ufy 47w+DIwUXTmb33sPMopKtAdWVqkobUSXvPO943aWqirbgPk0CljZto413gVvu8zfl7mi k81w== X-Gm-Message-State: AOAM5302biJV4KkdAKV+pF8hSnToMCN4xXxqnT67krE7SyKI/iH4tGF1 Lkg4yUzv7o7ylgFi7XWZ/lpTFo8556Efug== X-Google-Smtp-Source: ABdhPJyhgE0jqM93Q9glBx5zr2oitPx34fTQ646NYNBCLlHFa9uKBazTrFpDIlIgdcOjOZ0WNnIALg== X-Received: by 2002:a05:600c:4f49:b0:394:8125:8b6 with SMTP id m9-20020a05600c4f4900b00394812508b6mr10898849wmq.80.1652092879195; Mon, 09 May 2022 03:41:19 -0700 (PDT) Received: from ?IPV6:2a0b:e7c0:0:107::70f? ([2a0b:e7c0:0:107::70f]) by smtp.gmail.com with ESMTPSA id m37-20020a05600c3b2500b003942a244ec5sm12731163wms.10.2022.05.09.03.41.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 09 May 2022 03:41:18 -0700 (PDT) Message-ID: Date: Mon, 9 May 2022 12:41:17 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH 1/3] tty: n_gsm: fix buffer over-read in gsm_dlci_data() Content-Language: en-US To: "D. Starke" , linux-serial@vger.kernel.org, gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org References: <20220504081733.3494-1-daniel.starke@siemens.com> From: Jiri Slaby In-Reply-To: <20220504081733.3494-1-daniel.starke@siemens.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04. 05. 22, 10:17, D. Starke wrote: > From: Daniel Starke > > 'len' is decreased after each octet that has its EA bit set to 0, which > means that the value is encoded with additional octets. However, the final > octet does not decreases 'len' which results in 'len' being one byte too > long. A buffer over-read may occur in tty_insert_flip_string() as it tries > to read one byte more than the passed content size of 'data'. > Decrease 'len' also for the final octet which has the EA bit set to 1 to > write the correct number of bytes from the internal receive buffer to the > virtual tty. > > Fixes: 2e124b4a390c ("TTY: switch tty_flip_buffer_push") That commit barely introduced the problem. > Cc: stable@vger.kernel.org > Signed-off-by: Daniel Starke > --- > drivers/tty/n_gsm.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c > index a38b922bcbc1..9b0b435cf26e 100644 > --- a/drivers/tty/n_gsm.c > +++ b/drivers/tty/n_gsm.c > @@ -1658,6 +1658,7 @@ static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen) > if (len == 0) > return; > } > + len--; > slen++; > tty = tty_port_tty_get(port); > if (tty) { -- js suse labs