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 X-Spam-Level: X-Spam-Status: No, score=-10.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5D6A8C4363D for ; Fri, 25 Sep 2020 12:50:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1A244221EC for ; Fri, 25 Sep 2020 12:50:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601038203; bh=dokj4kC5+ub0lHtrLU8HkC5I0+L27AyzCasWDTasAgI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Q2wg4hHJBMGsuDhQnD8HimdB8AobsRwqyJI32+E55rpxToULSvsC0zWD1YuoBw7dj lZyMUnpUwS+nz79UGPaEju2SywTN2AmSBShy91KVMKeLnd8osNWrAbnR4yhICPBoPF j6lwVQU5MEoOkLjyZWKI9v7698WW8+ofrbO1s23M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728990AbgIYMuB (ORCPT ); Fri, 25 Sep 2020 08:50:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:53744 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728979AbgIYMt4 (ORCPT ); Fri, 25 Sep 2020 08:49:56 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7E2F2221EC; Fri, 25 Sep 2020 12:49:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601038196; bh=dokj4kC5+ub0lHtrLU8HkC5I0+L27AyzCasWDTasAgI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ghbesNr9UqILvxJESktP+vSOkotV9BDTPeCxN8DD/yCUgiDgiRF1padl6xuj/WabG 5KBKdeP2ovxf0CIrbm7XYzDCq8zD2CzOOj/4kxl5FrUy1rVVK8bNiK3KzuC3mN2YY3 GA/pInuFZAO6FJRKStgSXiD+O6l4nAm5b90kMgaA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, ChenNan Of Chaitin Security Research Lab , Dan Carpenter , Eric Dumazet , "David S. Miller" Subject: [PATCH 5.8 09/56] hdlc_ppp: add range checks in ppp_cp_parse_cr() Date: Fri, 25 Sep 2020 14:47:59 +0200 Message-Id: <20200925124729.228413251@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200925124727.878494124@linuxfoundation.org> References: <20200925124727.878494124@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: Dan Carpenter [ Upstream commit 66d42ed8b25b64eb63111a2b8582c5afc8bf1105 ] There are a couple bugs here: 1) If opt[1] is zero then this results in a forever loop. If the value is less than 2 then it is invalid. 2) It assumes that "len" is more than sizeof(valid_accm) or 6 which can result in memory corruption. In the case of LCP_OPTION_ACCM, then we should check "opt[1]" instead of "len" because, if "opt[1]" is less than sizeof(valid_accm) then "nak_len" gets out of sync and it can lead to memory corruption in the next iterations through the loop. In case of LCP_OPTION_MAGIC, the only valid value for opt[1] is 6, but the code is trying to log invalid data so we should only discard the data when "len" is less than 6 because that leads to a read overflow. Reported-by: ChenNan Of Chaitin Security Research Lab Fixes: e022c2f07ae5 ("WAN: new synchronous PPP implementation for generic HDLC.") Signed-off-by: Dan Carpenter Reviewed-by: Eric Dumazet Reviewed-by: Greg Kroah-Hartman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/wan/hdlc_ppp.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) --- a/drivers/net/wan/hdlc_ppp.c +++ b/drivers/net/wan/hdlc_ppp.c @@ -383,11 +383,8 @@ static void ppp_cp_parse_cr(struct net_d } for (opt = data; len; len -= opt[1], opt += opt[1]) { - if (len < 2 || len < opt[1]) { - dev->stats.rx_errors++; - kfree(out); - return; /* bad packet, drop silently */ - } + if (len < 2 || opt[1] < 2 || len < opt[1]) + goto err_out; if (pid == PID_LCP) switch (opt[0]) { @@ -395,6 +392,8 @@ static void ppp_cp_parse_cr(struct net_d continue; /* MRU always OK and > 1500 bytes? */ case LCP_OPTION_ACCM: /* async control character map */ + if (opt[1] < sizeof(valid_accm)) + goto err_out; if (!memcmp(opt, valid_accm, sizeof(valid_accm))) continue; @@ -406,6 +405,8 @@ static void ppp_cp_parse_cr(struct net_d } break; case LCP_OPTION_MAGIC: + if (len < 6) + goto err_out; if (opt[1] != 6 || (!opt[2] && !opt[3] && !opt[4] && !opt[5])) break; /* reject invalid magic number */ @@ -424,6 +425,11 @@ static void ppp_cp_parse_cr(struct net_d ppp_cp_event(dev, pid, RCR_GOOD, CP_CONF_ACK, id, req_len, data); kfree(out); + return; + +err_out: + dev->stats.rx_errors++; + kfree(out); } static int ppp_rx(struct sk_buff *skb)