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 63955CCA47D for ; Mon, 13 Jun 2022 19:32:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233949AbiFMTcP (ORCPT ); Mon, 13 Jun 2022 15:32:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33556 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239055AbiFMTb5 (ORCPT ); Mon, 13 Jun 2022 15:31:57 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 592A566AE5 for ; Mon, 13 Jun 2022 10:58:40 -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 ams.source.kernel.org (Postfix) with ESMTPS id 1A171B81236 for ; Mon, 13 Jun 2022 17:58:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 78C3CC34114; Mon, 13 Jun 2022 17:58:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1655143116; bh=Ld/BXRLYqmHqp6LHqcoocwRKV1tOSy4SiZmc4p+cX60=; h=Subject:To:Cc:From:Date:From; b=wNVI2/TXlbJzF0HL3EYIVUvjoAFfRfO/0fH/V6xokcK8t9SHkr/xXMhQSXmZzU+dX EMOVykPfKA8FyxXkwsKHZumrR3q44P5KJlTRhE+feDF+g/pLV8frYSd6UcxruITmES rOO4R/b4SE4xS8RTxpdfqG/RXCcDvQ2mJEqNoPpo= Subject: FAILED: patch "[PATCH] tcp: fix tcp_mtup_probe_success vs wrong snd_cwnd" failed to apply to 4.19-stable tree To: edumazet@google.com, davem@davemloft.net, ncardwell@google.com, syzkaller@googlegroups.com, ycheng@google.com Cc: From: Date: Mon, 13 Jun 2022 19:58:24 +0200 Message-ID: <16551431041632@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 11825765291a93d8e7f44230da67b9f607c777bf Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 27 May 2022 14:28:29 -0700 Subject: [PATCH] tcp: fix tcp_mtup_probe_success vs wrong snd_cwnd syzbot got a new report [1] finally pointing to a very old bug, added in initial support for MTU probing. tcp_mtu_probe() has checks about starting an MTU probe if tcp_snd_cwnd(tp) >= 11. But nothing prevents tcp_snd_cwnd(tp) to be reduced later and before the MTU probe succeeds. This bug would lead to potential zero-divides. Debugging added in commit 40570375356c ("tcp: add accessors to read/set tp->snd_cwnd") has paid off :) While we are at it, address potential overflows in this code. [1] WARNING: CPU: 1 PID: 14132 at include/net/tcp.h:1219 tcp_mtup_probe_success+0x366/0x570 net/ipv4/tcp_input.c:2712 Modules linked in: CPU: 1 PID: 14132 Comm: syz-executor.2 Not tainted 5.18.0-syzkaller-07857-gbabf0bb978e3 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:tcp_snd_cwnd_set include/net/tcp.h:1219 [inline] RIP: 0010:tcp_mtup_probe_success+0x366/0x570 net/ipv4/tcp_input.c:2712 Code: 74 08 48 89 ef e8 da 80 17 f9 48 8b 45 00 65 48 ff 80 80 03 00 00 48 83 c4 30 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 aa b0 c5 f8 <0f> 0b e9 16 fe ff ff 48 8b 4c 24 08 80 e1 07 38 c1 0f 8c c7 fc ff RSP: 0018:ffffc900079e70f8 EFLAGS: 00010287 RAX: ffffffff88c0f7f6 RBX: ffff8880756e7a80 RCX: 0000000000040000 RDX: ffffc9000c6c4000 RSI: 0000000000031f9e RDI: 0000000000031f9f RBP: 0000000000000000 R08: ffffffff88c0f606 R09: ffffc900079e7520 R10: ffffed101011226d R11: 1ffff1101011226c R12: 1ffff1100eadcf50 R13: ffff8880756e72c0 R14: 1ffff1100eadcf89 R15: dffffc0000000000 FS: 00007f643236e700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1ab3f1e2a0 CR3: 0000000064fe7000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: tcp_clean_rtx_queue+0x223a/0x2da0 net/ipv4/tcp_input.c:3356 tcp_ack+0x1962/0x3c90 net/ipv4/tcp_input.c:3861 tcp_rcv_established+0x7c8/0x1ac0 net/ipv4/tcp_input.c:5973 tcp_v6_do_rcv+0x57b/0x1210 net/ipv6/tcp_ipv6.c:1476 sk_backlog_rcv include/net/sock.h:1061 [inline] __release_sock+0x1d8/0x4c0 net/core/sock.c:2849 release_sock+0x5d/0x1c0 net/core/sock.c:3404 sk_stream_wait_memory+0x700/0xdc0 net/core/stream.c:145 tcp_sendmsg_locked+0x111d/0x3fc0 net/ipv4/tcp.c:1410 tcp_sendmsg+0x2c/0x40 net/ipv4/tcp.c:1448 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg net/socket.c:734 [inline] __sys_sendto+0x439/0x5c0 net/socket.c:2119 __do_sys_sendto net/socket.c:2131 [inline] __se_sys_sendto net/socket.c:2127 [inline] __x64_sys_sendto+0xda/0xf0 net/socket.c:2127 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f6431289109 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f643236e168 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f643139c100 RCX: 00007f6431289109 RDX: 00000000d0d0c2ac RSI: 0000000020000080 RDI: 000000000000000a RBP: 00007f64312e308d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff372533af R14: 00007f643236e300 R15: 0000000000022000 Fixes: 5d424d5a674f ("[TCP]: MTU probing") Signed-off-by: Eric Dumazet Reported-by: syzbot Acked-by: Yuchung Cheng Acked-by: Neal Cardwell Signed-off-by: David S. Miller diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 3231af73e430..2e2a9ece9af2 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2706,12 +2706,15 @@ static void tcp_mtup_probe_success(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); struct inet_connection_sock *icsk = inet_csk(sk); + u64 val; - /* FIXME: breaks with very large cwnd */ tp->prior_ssthresh = tcp_current_ssthresh(sk); - tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) * - tcp_mss_to_mtu(sk, tp->mss_cache) / - icsk->icsk_mtup.probe_size); + + val = (u64)tcp_snd_cwnd(tp) * tcp_mss_to_mtu(sk, tp->mss_cache); + do_div(val, icsk->icsk_mtup.probe_size); + DEBUG_NET_WARN_ON_ONCE((u32)val != val); + tcp_snd_cwnd_set(tp, max_t(u32, 1U, val)); + tp->snd_cwnd_cnt = 0; tp->snd_cwnd_stamp = tcp_jiffies32; tp->snd_ssthresh = tcp_current_ssthresh(sk);