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authorFlorian Westphal <fw@strlen.de>2020-04-29 21:43:20 +0300
committerDavid S. Miller <davem@davemloft.net>2020-04-29 22:39:49 +0300
commit42c556fef92361bbc58be22f91b1c49db0963c34 (patch)
treee077ddcb5cadbe3ed663100a8a0bd2c2060f72a6
parent9812307491231974f8eef1329237ce3d27da7462 (diff)
downloadlinux-42c556fef92361bbc58be22f91b1c49db0963c34.tar.xz
mptcp: replace mptcp_disconnect with a stub
Paolo points out that mptcp_disconnect is bogus: "lock_sock(sk); looks suspicious (lock should be already held by the caller) And call to: tcp_disconnect(sk, flags); too, sk is not a tcp socket". ->disconnect() gets called from e.g. inet_stream_connect when one tries to disassociate a connected socket again (to re-connect without closing the socket first). MPTCP however uses mptcp_stream_connect, not inet_stream_connect, for the mptcp-socket connect call. inet_stream_connect only gets called indirectly, for the tcp socket, so any ->disconnect() calls end up calling tcp_disconnect for that tcp subflow sk. This also explains why syzkaller has not yet reported a problem here. So for now replace this with a stub that doesn't do anything. Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/14 Acked-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/mptcp/protocol.c11
1 files changed, 6 insertions, 5 deletions
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index b22a63ba2348..6e0188f5d3f3 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1316,11 +1316,12 @@ static void mptcp_copy_inaddrs(struct sock *msk, const struct sock *ssk)
static int mptcp_disconnect(struct sock *sk, int flags)
{
- lock_sock(sk);
- __mptcp_clear_xmit(sk);
- release_sock(sk);
- mptcp_cancel_work(sk);
- return tcp_disconnect(sk, flags);
+ /* Should never be called.
+ * inet_stream_connect() calls ->disconnect, but that
+ * refers to the subflow socket, not the mptcp one.
+ */
+ WARN_ON_ONCE(1);
+ return 0;
}
#if IS_ENABLED(CONFIG_MPTCP_IPV6)