From nobody Thu Jan 2 15:50:12 2025 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 73B871A0B08 for ; Sat, 21 Dec 2024 08:53:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734771183; cv=none; b=eTWhaW06edcPeJmL87SMGloT7dw8INdrnDXPYdWFIP7rfOUS3CD4X9dVTw/pYnrWj06QK3xGYg9nLL8qYmkRQQVamCzcG/Hz5PxCD50t8vTdqt6OAdhbiSnrBvk5RFnB4kQIaCS0CfZMYuVYkqungiseaQmX6G8J0uaGsOhzVVk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734771183; c=relaxed/simple; bh=cjKF2C9TZmQVmts5DW4GLLkPodNlIEAgBCccDDu79Is=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=KBimanAHJGLi/MfLNGnrR5Kittk4HgioUTE93IJwt1dCO5iItKWPfB4+GNj4Wr2ZfhN8Ps7KaPk8DxHcczOekEdjdgbi0k2AnaSo7oVzC2WtBe3MOva8rEZcG+41QpDJ1N7d3bbDagL+DbZrwlvqbe5sidgHzY87NAgSlYLTAV4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=RGRiTUck; arc=none smtp.client-ip=170.10.133.124 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="RGRiTUck" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1734771180; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=5u7ODnEiVmrU6NmFwmTtOY2PwDk2M+piTrUPkLuAqSY=; b=RGRiTUckqQSW6USzK3cw8PvnWjmxbtfGM0wJYBIS/kRoCN4joIplGheASEj6yWpxF8ONeF ixiWmkAU7GLmAdE0f/s8mZ8m/iH3t2OgSjsgrwCPDg5uIomq8wbK4WbZ/HTfoG5BZOT/87 hJ3uXYEDHuwBy5WZOfwChhvdqQwZedg= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-492-uDYhupN2OKC2e8CdgsnKUg-1; Sat, 21 Dec 2024 03:52:56 -0500 X-MC-Unique: uDYhupN2OKC2e8CdgsnKUg-1 X-Mimecast-MFC-AGG-ID: uDYhupN2OKC2e8CdgsnKUg Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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 mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7012B1956096; Sat, 21 Dec 2024 08:52:54 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.39.192.36]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 1373A19560A2; Sat, 21 Dec 2024 08:52:50 +0000 (UTC) From: Paolo Abeni To: netdev@vger.kernel.org Cc: Matthieu Baerts , Mat Martineau , Geliang Tang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Simon Horman , mptcp@lists.linux.dev Subject: [PATCH net] mptcp: fix TCP options overflow. Date: Sat, 21 Dec 2024 09:51:46 +0100 Message-ID: <025d9df8cde3c9a557befc47e9bc08fbbe3476e5.1734771049.git.pabeni@redhat.com> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Content-Type: text/plain; charset="utf-8" Syzbot reported the following splat: Oops: general protection fault, probably for non-canonical address 0xdffffc= 0000000001: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 1 UID: 0 PID: 5836 Comm: sshd Not tainted 6.13.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Goo= gle 11/25/2024 RIP: 0010:_compound_head include/linux/page-flags.h:242 [inline] RIP: 0010:put_page+0x23/0x260 include/linux/mm.h:1552 Code: 90 90 90 90 90 90 90 55 41 57 41 56 53 49 89 fe 48 bd 00 00 00 00 00 = fc ff df e8 f8 5e 12 f8 49 8d 5e 08 48 89 d8 48 c1 e8 03 <80> 3c 28 00 74 0= 8 48 89 df e8 8f c7 78 f8 48 8b 1b 48 89 de 48 83 RSP: 0000:ffffc90003916c90 EFLAGS: 00010202 RAX: 0000000000000001 RBX: 0000000000000008 RCX: ffff888030458000 RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000 RBP: dffffc0000000000 R08: ffffffff898ca81d R09: 1ffff110054414ac R10: dffffc0000000000 R11: ffffed10054414ad R12: 0000000000000007 R13: ffff88802a20a542 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f34f496e800(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9d6ec9ec28 CR3: 000000004d260000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: skb_page_unref include/linux/skbuff_ref.h:43 [inline] __skb_frag_unref include/linux/skbuff_ref.h:56 [inline] skb_release_data+0x483/0x8a0 net/core/skbuff.c:1119 skb_release_all net/core/skbuff.c:1190 [inline] __kfree_skb+0x55/0x70 net/core/skbuff.c:1204 tcp_clean_rtx_queue net/ipv4/tcp_input.c:3436 [inline] tcp_ack+0x2442/0x6bc0 net/ipv4/tcp_input.c:4032 tcp_rcv_state_process+0x8eb/0x44e0 net/ipv4/tcp_input.c:6805 tcp_v4_do_rcv+0x77d/0xc70 net/ipv4/tcp_ipv4.c:1939 tcp_v4_rcv+0x2dc0/0x37f0 net/ipv4/tcp_ipv4.c:2351 ip_protocol_deliver_rcu+0x22e/0x440 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x341/0x5f0 net/ipv4/ip_input.c:233 NF_HOOK+0x3a4/0x450 include/linux/netfilter.h:314 NF_HOOK+0x3a4/0x450 include/linux/netfilter.h:314 __netif_receive_skb_one_core net/core/dev.c:5672 [inline] __netif_receive_skb+0x2bf/0x650 net/core/dev.c:5785 process_backlog+0x662/0x15b0 net/core/dev.c:6117 __napi_poll+0xcb/0x490 net/core/dev.c:6883 napi_poll net/core/dev.c:6952 [inline] net_rx_action+0x89b/0x1240 net/core/dev.c:7074 handle_softirqs+0x2d4/0x9b0 kernel/softirq.c:561 __do_softirq kernel/softirq.c:595 [inline] invoke_softirq kernel/softirq.c:435 [inline] __irq_exit_rcu+0xf7/0x220 kernel/softirq.c:662 irq_exit_rcu+0x9/0x30 kernel/softirq.c:678 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0x57/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:= 702 RIP: 0033:0x7f34f4519ad5 Code: 85 d2 74 0d 0f 10 02 48 8d 54 24 20 0f 11 44 24 20 64 8b 04 25 18 00 = 00 00 85 c0 75 27 41 b8 08 00 00 00 b8 0f 01 00 00 0f 05 <48> 3d 00 f0 ff f= f 76 75 48 8b 15 24 73 0d 00 f7 d8 64 89 02 48 83 RSP: 002b:00007ffec5b32ce0 EFLAGS: 00000246 RAX: 0000000000000001 RBX: 00000000000668a0 RCX: 00007f34f4519ad5 RDX: 00007ffec5b32d00 RSI: 0000000000000004 RDI: 0000564f4bc6cae0 RBP: 0000564f4bc6b5a0 R08: 0000000000000008 R09: 0000000000000000 R10: 00007ffec5b32de8 R11: 0000000000000246 R12: 0000564f48ea8aa4 R13: 0000000000000001 R14: 0000564f48ea93e8 R15: 00007ffec5b32d68 Eric noted a probable shinfo->nr_frags corruption, which indeed occurs. The root cause is a buggy MPTCP option len computation in some circumstances: the ADD_ADDR option should be mutually exclusive with DSS since the blamed commit. Still, mptcp_established_options_add_addr() tries to set the relevant info in mptcp_out_options, if the remaining space is large enough even when DSS is present. Since the ADD_ADDR infos and the DSS share the same union fields, adding first corrupts the latter. In the worst-case scenario, such corruption increases the DSS binary layout, exceeding the computed length and possibly overwriting the skb shared info. Address the issue by enforcing mutual exclusion in mptcp_established_options_add_addr(), too. Reported-by: syzbot+38a095a81f30d82884c1@syzkaller.appspotmail.com Fixes: 1bff1e43a30e ("mptcp: optimize out option generation") Signed-off-by: Paolo Abeni Reviewed-by: Eric Dumazet Reviewed-by: Matthieu Baerts (NGI0) --- net/mptcp/options.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/mptcp/options.c b/net/mptcp/options.c index ad22622843a2..9ea7356d9fab 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -667,8 +667,15 @@ static bool mptcp_established_options_add_addr(struct = sock *sk, struct sk_buff * &echo, &drop_other_suboptions)) return false; =20 + /* + * Later on, mptcp_write_options() will enforce mutually exclusion with + * DSS, bail out if such option is set and we can't drop it. + */ if (drop_other_suboptions) remaining +=3D opt_size; + else if (opts->suboptions & OPTION_MPTCP_DSS) + return false; + len =3D mptcp_add_addr_len(opts->addr.family, echo, !!opts->addr.port); if (remaining < len) return false; --=20 2.45.2