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mptcp: reset 'first' and ack_hint on subflow close 

Just like with last_snd, we have to NULL 'first' on subflow close.

ack_hint isn't strictly required (its never dereferenced), but better to
clear this explicitly as well instead of making it an exception.

msk->first is dereferenced unconditionally at accept time, but
at that point the ssk is not on the conn_list yet -- this means
worker can't see it when iterating the conn_list.

Reported-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Florian Westphal 2021-03-04 13:32:12 -08:00 committed by David S. Miller
parent 17aee05dc8
commit c8fe62f076
1 changed files with 9 additions and 0 deletions
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9
net/mptcp/protocol.c
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@ -2169,6 +2169,12 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
if (ssk == msk->last_snd)
msk->last_snd = NULL;
if (ssk == msk->ack_hint)
msk->ack_hint = NULL;
if (ssk == msk->first)
msk->first = NULL;
if (msk->subflow && ssk == msk->subflow->sk)
mptcp_dispose_initial_subflow(msk);
}
@ -3297,6 +3303,9 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
/* PM/worker can now acquire the first subflow socket
* lock without racing with listener queue cleanup,
* we can notify it, if needed.
*
* Even if remote has reset the initial subflow by now
* the refcnt is still at least one.
*/
subflow = mptcp_subflow_ctx(msk->first);
list_add(&subflow->node, &msk->conn_list);