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_PASS,URIBL_BLOCKED autolearn=ham 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 0D4ADC71122 for ; Sun, 14 Oct 2018 15:52:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D3E0A20645 for ; Sun, 14 Oct 2018 15:52:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D3E0A20645 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727961AbeJNXL6 (ORCPT ); Sun, 14 Oct 2018 19:11:58 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:36076 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727761AbeJNXL4 (ORCPT ); Sun, 14 Oct 2018 19:11:56 -0400 Received: from [2a02:8011:400e:2:cbab:f00:c93f:614] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1gBiLj-0004cU-Ow; Sun, 14 Oct 2018 16:30:36 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gBiLZ-0000hm-Q2; Sun, 14 Oct 2018 16:30:25 +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, "Neal Cardwell" , "syzbot" , "Yuchung Cheng" , "David S. Miller" , "Eric Dumazet" Date: Sun, 14 Oct 2018 16:25:41 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 323/366] tcp: purge write queue in tcp_connect_init() In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:cbab:f00:c93f:614 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.60-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit 7f582b248d0a86bae5788c548d7bb5bca6f7691a upstream. syzkaller found a reliable way to crash the host, hitting a BUG() in __tcp_retransmit_skb() Malicous MSG_FASTOPEN is the root cause. We need to purge write queue in tcp_connect_init() at the point we init snd_una/write_seq. This patch also replaces the BUG() by a less intrusive WARN_ON_ONCE() kernel BUG at net/ipv4/tcp_output.c:2837! invalid opcode: 0000 [#1] SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 0 PID: 5276 Comm: syz-executor0 Not tainted 4.17.0-rc3+ #51 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__tcp_retransmit_skb+0x2992/0x2eb0 net/ipv4/tcp_output.c:2837 RSP: 0000:ffff8801dae06ff8 EFLAGS: 00010206 RAX: ffff8801b9fe61c0 RBX: 00000000ffc18a16 RCX: ffffffff864e1a49 RDX: 0000000000000100 RSI: ffffffff864e2e12 RDI: 0000000000000005 RBP: ffff8801dae073a0 R08: ffff8801b9fe61c0 R09: ffffed0039c40dd2 R10: ffffed0039c40dd2 R11: ffff8801ce206e93 R12: 00000000421eeaad R13: ffff8801ce206d4e R14: ffff8801ce206cc0 R15: ffff8801cd4f4a80 FS: 0000000000000000(0000) GS:ffff8801dae00000(0063) knlGS:00000000096bc900 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 0000000020000000 CR3: 00000001c47b6000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: tcp_retransmit_skb+0x2e/0x250 net/ipv4/tcp_output.c:2923 tcp_retransmit_timer+0xc50/0x3060 net/ipv4/tcp_timer.c:488 tcp_write_timer_handler+0x339/0x960 net/ipv4/tcp_timer.c:573 tcp_write_timer+0x111/0x1d0 net/ipv4/tcp_timer.c:593 call_timer_fn+0x230/0x940 kernel/time/timer.c:1326 expire_timers kernel/time/timer.c:1363 [inline] __run_timers+0x79e/0xc50 kernel/time/timer.c:1666 run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692 __do_softirq+0x2e0/0xaf5 kernel/softirq.c:285 invoke_softirq kernel/softirq.c:365 [inline] irq_exit+0x1d1/0x200 kernel/softirq.c:405 exiting_irq arch/x86/include/asm/apic.h:525 [inline] smp_apic_timer_interrupt+0x17e/0x710 arch/x86/kernel/apic/apic.c:1052 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863 Fixes: cf60af03ca4e ("net-tcp: Fast Open client - sendmsg(MSG_FASTOPEN)") Signed-off-by: Eric Dumazet Cc: Yuchung Cheng Cc: Neal Cardwell Reported-by: syzbot Acked-by: Neal Cardwell Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- net/ipv4/tcp_output.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2450,8 +2450,10 @@ int __tcp_retransmit_skb(struct sock *sk return -EBUSY; if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { - if (before(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) - BUG(); + if (unlikely(before(TCP_SKB_CB(skb)->end_seq, tp->snd_una))) { + WARN_ON_ONCE(1); + return -EINVAL; + } if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) return -ENOMEM; } @@ -2948,6 +2950,7 @@ static void tcp_connect_init(struct sock sock_reset_flag(sk, SOCK_DONE); tp->snd_wnd = 0; tcp_init_wl(tp, 0); + tcp_write_queue_purge(sk); tp->snd_una = tp->write_seq; tp->snd_sml = tp->write_seq; tp->snd_up = tp->write_seq;