Re: [PATCH mptcp] mptcp: remove tcp ulp setsockopt support
flat view
From: Jakub Kicinski <kuba@kernel.org>
Date: 2021-12-06 16:03:28
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On Mon, 6 Dec 2021 07:53:26 -0800 Jakub Kicinski wrote:
On Sun, 5 Dec 2021 20:27:00 +0100 Florian Westphal wrote:quoted
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.
quoted
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@syzkaller.appspotmail.com Signed-off-by: Florian Westphal <fw@strlen.de>