From nobody Thu May 9 03:58:54 2024 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1DB94BE48 for ; Fri, 27 Oct 2023 14:21:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="MGEqGiyd" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1698416500; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=Ym/0GD2apwHjK1ghy8HuQ9V6sMruunHDaWAgyt7IiI0=; b=MGEqGiydAR1kunbvVc9iIYxb8+qny86FASYDw78G2JdFonM66Il8iT5SA4Pgv/JpMTAAyW JPO1N7dcbSLM4sz4i2VMwmnov1MrysksKvSL0KTzZyjYN2OrIrt5gM1FkYZlJxhkRVkauE fT7P7CylI1al8Z7DcFUiplHPfgnevTQ= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-439-KFTmLvT-OpWkAyhA7YrsZw-1; Fri, 27 Oct 2023 10:21:39 -0400 X-MC-Unique: KFTmLvT-OpWkAyhA7YrsZw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 34048101FAA1; Fri, 27 Oct 2023 14:21:39 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.45.226.143]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8AB8D40C6F79; Fri, 27 Oct 2023 14:21:38 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Cc: Christoph Paasch Subject: [PATCH net-next] mptcp: deal with large GSO size. Date: Fri, 27 Oct 2023 16:21:36 +0200 Message-ID: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8"; x-default="true" After the blamed commit below, the TCP sockets (and the MPTCP subflows) can build egress packets larger then 64K. That exceeds the maximum DSS data size, the length being misrepresent on the wire and the stream being corrupted, as later observed on the receiver: WARNING: CPU: 0 PID: 9696 at net/mptcp/protocol.c:705 __mptcp_move_skbs_fro= m_subflow+0x2604/0x26e0 CPU: 0 PID: 9696 Comm: syz-executor.7 Not tainted 6.6.0-rc5-gcd8bdf563d46 #= 45 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04= /01/2014 netlink: 8 bytes leftover after parsing attributes in process `syz-executor= .4'. RIP: 0010:__mptcp_move_skbs_from_subflow+0x2604/0x26e0 net/mptcp/protocol.c= :705 RSP: 0018:ffffc90000006e80 EFLAGS: 00010246 RAX: ffffffff83e9f674 RBX: ffff88802f45d870 RCX: ffff888102ad0000 netlink: 8 bytes leftover after parsing attributes in process `syz-executor= .4'. RDX: 0000000080000303 RSI: 0000000000013908 RDI: 0000000000003908 RBP: ffffc90000007110 R08: ffffffff83e9e078 R09: 1ffff1100e548c8a R10: dffffc0000000000 R11: ffffed100e548c8b R12: 0000000000013908 R13: dffffc0000000000 R14: 0000000000003908 R15: 000000000031cf29 FS: 00007f239c47e700(0000) GS:ffff88811b200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f239c45cd78 CR3: 000000006a66c006 CR4: 0000000000770ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 PKRU: 55555554 Call Trace: mptcp_data_ready+0x263/0xac0 net/mptcp/protocol.c:819 subflow_data_ready+0x268/0x6d0 net/mptcp/subflow.c:1409 tcp_data_queue+0x21a1/0x7a60 net/ipv4/tcp_input.c:5151 tcp_rcv_established+0x950/0x1d90 net/ipv4/tcp_input.c:6098 tcp_v6_do_rcv+0x554/0x12f0 net/ipv6/tcp_ipv6.c:1483 tcp_v6_rcv+0x2e26/0x3810 net/ipv6/tcp_ipv6.c:1749 ip6_protocol_deliver_rcu+0xd6b/0x1ae0 net/ipv6/ip6_input.c:438 ip6_input+0x1c5/0x470 net/ipv6/ip6_input.c:483 ipv6_rcv+0xef/0x2c0 include/linux/netfilter.h:304 __netif_receive_skb+0x1ea/0x6a0 net/core/dev.c:5532 process_backlog+0x353/0x660 net/core/dev.c:5974 __napi_poll+0xc6/0x5a0 net/core/dev.c:6536 net_rx_action+0x6a0/0xfd0 net/core/dev.c:6603 __do_softirq+0x184/0x524 kernel/softirq.c:553 do_softirq+0xdd/0x130 kernel/softirq.c:454 Address the issue explicitly bounding the maximum GSO size to what MPTCP actually allows. Reported-by: Christoph Paasch Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/450 Fixes: 7c4e983c4f3c ("net: allow gso_max_size to exceed 65536") Signed-off-by: Paolo Abeni Reviewed-by: Mat Martineau --- this is a rough quick attempt to address the issue. A cleaner one would be catching sk_gso_max_size in the control path and bound the value there. Done this way to: - allow earlier testing - create a much smaller patch. --- net/mptcp/protocol.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index b41f8c3e0c00..d522fabc863d 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1234,6 +1234,8 @@ static void mptcp_update_infinite_map(struct mptcp_so= ck *msk, mptcp_do_fallback(ssk); } =20 +#define MPTCP_MAX_GSO_SIZE (GSO_LEGACY_MAX_SIZE - (MAX_TCP_HEADER + 1)) + static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, struct mptcp_data_frag *dfrag, struct mptcp_sendmsg_info *info) @@ -1260,6 +1262,8 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct= sock *ssk, return -EAGAIN; =20 /* compute send limit */ + if (unlikely(ssk->sk_gso_max_size > MPTCP_MAX_GSO_SIZE)) + ssk->sk_gso_max_size =3D MPTCP_MAX_GSO_SIZE; info->mss_now =3D tcp_send_mss(ssk, &info->size_goal, info->flags); copy =3D info->size_goal; =20 --=20 2.41.0