linux-kernel - Re: [PATCH mptcp] mptcp: remove tcp ulp setsockopt support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20211206075515.3cf5b0df@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Mon, 6 Dec 2021 07:55:15 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Florian Westphal <fw@...len.de>
Cc:     <mptcp@...ts.linux.dev>, syzkaller-bugs@...glegroups.com,
        <netdev@...r.kernel.org>, linux-kernel@...r.kernel.org,
        syzbot+1fd9b69cde42967d1add@...kaller.appspotmail.com
Subject: Re: [PATCH mptcp] mptcp: remove tcp ulp setsockopt support

On Mon, 6 Dec 2021 07:53:26 -0800 Jakub Kicinski wrote:
> On Sun,  5 Dec 2021 20:27:00 +0100 Florian Westphal wrote:
> > TCP_ULP setsockopt cannot be used for mptcp because its already
> > used internally to plumb subflow (tcp) sockets to the mptcp layer.
> > 
> > syzbot managed to trigger a crash for mptcp connections that are
> > in fallback mode:  
> 
> Fallback mode meaning ops are NULL? I'm slightly confused by this
> report.

Ah, it's the socket not the ops.

> > KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
> > CPU: 1 PID: 1083 Comm: syz-executor.3 Not tainted 5.16.0-rc2-syzkaller #0
> > RIP: 0010:tls_build_proto net/tls/tls_main.c:776 [inline]
> > [..]
> >  __tcp_set_ulp net/ipv4/tcp_ulp.c:139 [inline]
> >  tcp_set_ulp+0x428/0x4c0 net/ipv4/tcp_ulp.c:160
> >  do_tcp_setsockopt+0x455/0x37c0 net/ipv4/tcp.c:3391
> >  mptcp_setsockopt+0x1b47/0x2400 net/mptcp/sockopt.c:638
> > 
> > Remove support for TCP_ULP setsockopt.
> > 
> > Reported-by: syzbot+1fd9b69cde42967d1add@...kaller.appspotmail.com
> > Signed-off-by: Florian Westphal <fw@...len.de>