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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 221B1C31E5D for ; Tue, 18 Jun 2019 14:29:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 02BC4213F2 for ; Tue, 18 Jun 2019 14:29:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729496AbfFRO3f (ORCPT ); Tue, 18 Jun 2019 10:29:35 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:50506 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729395AbfFRO3H (ORCPT ); Tue, 18 Jun 2019 10:29:07 -0400 Received: from [167.98.27.226] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1hdF6e-0007nL-6i; Tue, 18 Jun 2019 15:29:04 +0100 Received: from ben by deadeye with local (Exim 4.92) (envelope-from ) id 1hdF6d-0000Hl-LZ; Tue, 18 Jun 2019 15:29:03 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "David S. Miller" , "Jonathan Lemon" , "Jonathan Looney" , "Yuchung Cheng" , "Eric Dumazet" , "Tyler Hicks" , "Neal Cardwell" , "Bruce Curtis" Date: Tue, 18 Jun 2019 15:28:02 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 08/10] tcp: tcp_fragment() should apply sane memory limits In-Reply-To: X-SA-Exim-Connect-IP: 167.98.27.226 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 3.16.69-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit f070ef2ac66716357066b683fb0baf55f8191a2e upstream. Jonathan Looney reported that a malicious peer can force a sender to fragment its retransmit queue into tiny skbs, inflating memory usage and/or overflow 32bit counters. TCP allows an application to queue up to sk_sndbuf bytes, so we need to give some allowance for non malicious splitting of retransmit queue. A new SNMP counter is added to monitor how many times TCP did not allow to split an skb if the allowance was exceeded. Note that this counter might increase in the case applications use SO_SNDBUF socket option to lower sk_sndbuf. CVE-2019-11478 : tcp_fragment, prevent fragmenting a packet when the socket is already using more than half the allowed space Signed-off-by: Eric Dumazet Reported-by: Jonathan Looney Acked-by: Neal Cardwell Acked-by: Yuchung Cheng Reviewed-by: Tyler Hicks Cc: Bruce Curtis Cc: Jonathan Lemon Signed-off-by: David S. Miller [Salvatore Bonaccorso: Adjust context for backport to 4.9.168] [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- include/uapi/linux/snmp.h | 1 + net/ipv4/proc.c | 1 + net/ipv4/tcp_output.c | 5 +++++ 3 files changed, 7 insertions(+) --- a/include/uapi/linux/snmp.h +++ b/include/uapi/linux/snmp.h @@ -265,6 +265,7 @@ enum LINUX_MIB_TCPWANTZEROWINDOWADV, /* TCPWantZeroWindowAdv */ LINUX_MIB_TCPSYNRETRANS, /* TCPSynRetrans */ LINUX_MIB_TCPORIGDATASENT, /* TCPOrigDataSent */ + LINUX_MIB_TCPWQUEUETOOBIG, /* TCPWqueueTooBig */ __LINUX_MIB_MAX }; --- a/net/ipv4/proc.c +++ b/net/ipv4/proc.c @@ -286,6 +286,7 @@ static const struct snmp_mib snmp4_net_l SNMP_MIB_ITEM("TCPWantZeroWindowAdv", LINUX_MIB_TCPWANTZEROWINDOWADV), SNMP_MIB_ITEM("TCPSynRetrans", LINUX_MIB_TCPSYNRETRANS), SNMP_MIB_ITEM("TCPOrigDataSent", LINUX_MIB_TCPORIGDATASENT), + SNMP_MIB_ITEM("TCPWqueueTooBig", LINUX_MIB_TCPWQUEUETOOBIG), SNMP_MIB_SENTINEL }; --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1090,6 +1090,11 @@ int tcp_fragment(struct sock *sk, struct if (nsize < 0) nsize = 0; + if (unlikely((sk->sk_wmem_queued >> 1) > sk->sk_sndbuf)) { + NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPWQUEUETOOBIG); + return -ENOMEM; + } + if (skb_unclone(skb, gfp)) return -ENOMEM;