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 09932C433F5 for ; Wed, 4 May 2022 16:54:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354349AbiEDQ5w (ORCPT ); Wed, 4 May 2022 12:57:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51880 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349590AbiEDQyY (ORCPT ); Wed, 4 May 2022 12:54:24 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7531A4968D; Wed, 4 May 2022 09:49:36 -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 146896174C; Wed, 4 May 2022 16:49:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 653FCC385A4; Wed, 4 May 2022 16:49:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1651682975; bh=L1Ds1EUngD0M7E8EcZPz2evcTmB11XeoOhit7RNR7g8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ExOx4PC8GMGJev/cSHaKz283lrrtBp6k/9H7Wcssu5qWqP94MMaAz3aFm5V6kyOHN W2EFKHXmkHgbf2FWBopCNsrjsE7M4SgvVE7GFR38s0ZnehJUzbZytD7pvHrpY9KUiq Mq37SPCGjMw0ZZPfRDS2Y9M2TNCSL3yNX0M+chGs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Starke Subject: [PATCH 5.4 78/84] tty: n_gsm: fix insufficient txframe size Date: Wed, 4 May 2022 18:44:59 +0200 Message-Id: <20220504152933.672339990@linuxfoundation.org> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220504152927.744120418@linuxfoundation.org> References: <20220504152927.744120418@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 535bf600de75a859698892ee873521a48d289ec1 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 5.7.2 states that the maximum frame size (N1) refers to the length of the information field (i.e. user payload). However, 'txframe' stores the whole frame including frame header, checksum and start/end flags. We also need to consider the byte stuffing overhead. Define constant for the protocol overhead and adjust the 'txframe' size calculation accordingly to reserve enough space for a complete mux frame including byte stuffing for advanced option mode. Note that no byte stuffing is applied to the start and end flag. Also use MAX_MTU instead of MAX_MRU as this buffer is used for data transmission. Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke Link: https://lore.kernel.org/r/20220414094225.4527-8-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_gsm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -72,6 +72,8 @@ module_param(debug, int, 0600); */ #define MAX_MRU 1500 #define MAX_MTU 1500 +/* SOF, ADDR, CTRL, LEN1, LEN2, ..., FCS, EOF */ +#define PROT_OVERHEAD 7 #define GSM_NET_TX_TIMEOUT (HZ*10) /** @@ -2209,7 +2211,7 @@ static struct gsm_mux *gsm_alloc_mux(voi kfree(gsm); return NULL; } - gsm->txframe = kmalloc(2 * MAX_MRU + 2, GFP_KERNEL); + gsm->txframe = kmalloc(2 * (MAX_MTU + PROT_OVERHEAD - 1), GFP_KERNEL); if (gsm->txframe == NULL) { kfree(gsm->buf); kfree(gsm);