Patch "net/ulp: prevent ULP without clone op from entering the LISTEN status" has been added to the 6.0-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    net/ulp: prevent ULP without clone op from entering the LISTEN status

to the 6.0-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-ulp-prevent-ulp-without-clone-op-from-entering-t.patch
and it can be found in the queue-6.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit f8fe8d7f6ff95585691e842effc095f5eb30bb65
Author: Paolo Abeni <pabeni@xxxxxxxxxx>
Date:   Tue Jan 3 12:19:17 2023 +0100

    net/ulp: prevent ULP without clone op from entering the LISTEN status
    
    [ Upstream commit 2c02d41d71f90a5168391b6a5f2954112ba2307c ]
    
    When an ULP-enabled socket enters the LISTEN status, the listener ULP data
    pointer is copied inside the child/accepted sockets by sk_clone_lock().
    
    The relevant ULP can take care of de-duplicating the context pointer via
    the clone() operation, but only MPTCP and SMC implement such op.
    
    Other ULPs may end-up with a double-free at socket disposal time.
    
    We can't simply clear the ULP data at clone time, as TLS replaces the
    socket ops with custom ones assuming a valid TLS ULP context is
    available.
    
    Instead completely prevent clone-less ULP sockets from entering the
    LISTEN status.
    
    Fixes: 734942cc4ea6 ("tcp: ULP infrastructure")
    Reported-by: slipper <slipper.alive@xxxxxxxxx>
    Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/4b80c3d1dbe3d0ab072f80450c202d9bc88b4b03.1672740602.git.pabeni@xxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 971969cc7e17..fb01211a255b 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -1037,12 +1037,26 @@ void inet_csk_prepare_forced_close(struct sock *sk)
 }
 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
 
+static int inet_ulp_can_listen(const struct sock *sk)
+{
+	const struct inet_connection_sock *icsk = inet_csk(sk);
+
+	if (icsk->icsk_ulp_ops && !icsk->icsk_ulp_ops->clone)
+		return -EINVAL;
+
+	return 0;
+}
+
 int inet_csk_listen_start(struct sock *sk)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	struct inet_sock *inet = inet_sk(sk);
 	int err;
 
+	err = inet_ulp_can_listen(sk);
+	if (unlikely(err))
+		return err;
+
 	reqsk_queue_alloc(&icsk->icsk_accept_queue);
 
 	sk->sk_ack_backlog = 0;
diff --git a/net/ipv4/tcp_ulp.c b/net/ipv4/tcp_ulp.c
index 9ae50b1bd844..05b6077b9f2c 100644
--- a/net/ipv4/tcp_ulp.c
+++ b/net/ipv4/tcp_ulp.c
@@ -139,6 +139,10 @@ static int __tcp_set_ulp(struct sock *sk, const struct tcp_ulp_ops *ulp_ops)
 	if (sk->sk_socket)
 		clear_bit(SOCK_SUPPORT_ZC, &sk->sk_socket->flags);
 
+	err = -EINVAL;
+	if (!ulp_ops->clone && sk->sk_state == TCP_LISTEN)
+		goto out_err;
+
 	err = ulp_ops->init(sk);
 	if (err)
 		goto out_err;