Commit 17aee05d authored by Florian Westphal's avatar Florian Westphal Committed by David S. Miller
Browse files

mptcp: dispose initial struct socket when its subflow is closed 

Christoph Paasch reported following crash:
dst_release underflow
WARNING: CPU: 0 PID: 1319 at net/core/dst.c:175 dst_release+0xc1/0xd0 net/core/dst.c:175
CPU: 0 PID: 1319 Comm: syz-executor217 Not tainted 5.11.0-rc6af8e85128b4d0d24083c5cac646e891227052e0c #70
Call Trace:
 rt_cache_route+0x12e/0x140 net/ipv4/route.c:1503
 rt_set_nexthop.constprop.0+0x1fc/0x590 net/ipv4/route.c:1612
 __mkroute_output net/ipv4/route.c:2484 [inline]
...

The worker leaves msk->subflow alone even when it
happened to close the subflow ssk associated with it.

Fixes: 866f26f2 ("mptcp: always graft subflow socket to parent")
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/157


Reported-by: default avatarChristoph Paasch <cpaasch@apple.com>
Suggested-by: default avatarPaolo Abeni <pabeni@redhat.com>
Acked-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent eaeef1ce

net/mptcp/protocol.c

+12 −6
Original line number Diff line number Diff line
@@ -2116,6 +2116,14 @@ static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk) 
	return backup;

}



static void mptcp_dispose_initial_subflow(struct mptcp_sock *msk)

{

	if (msk->subflow) {

		iput(SOCK_INODE(msk->subflow));

		msk->subflow = NULL;

	}

}



/* subflow sockets can be either outgoing (connect) or incoming

 * (accept).

 *
@@ -2160,6 +2168,9 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk, 


	if (ssk == msk->last_snd)

		msk->last_snd = NULL;



	if (msk->subflow && ssk == msk->subflow->sk)

		mptcp_dispose_initial_subflow(msk);

}



void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
@@ -2529,12 +2540,6 @@ static void __mptcp_destroy_sock(struct sock *sk) 


	might_sleep();



	/* dispose the ancillatory tcp socket, if any */

	if (msk->subflow) {

		iput(SOCK_INODE(msk->subflow));

		msk->subflow = NULL;

	}



	/* be sure to always acquire the join list lock, to sync vs

	 * mptcp_finish_join().

	 */
@@ -2559,6 +2564,7 @@ static void __mptcp_destroy_sock(struct sock *sk) 
	sk_stream_kill_queues(sk);

	xfrm_sk_free_policy(sk);

	sk_refcnt_debug_release(sk);

	mptcp_dispose_initial_subflow(msk);

	sock_put(sk);

}