5.15-stable review patch. If anyone has any objections, please let me know.
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From: "Matthieu Baerts (NGI0)" matttbe@kernel.org
commit d82809b6c5f2676b382f77a5cbeb1a5d91ed2235 upstream.
The initial subflow might have already been closed, but still in the connection list. When the worker is instructed to close the subflows that have been marked as closed, it might then try to close the initial subflow again.
A consequence of that is that the SUB_CLOSED event can be seen twice:
# ip mptcp endpoint 1.1.1.1 id 1 subflow dev eth0 2.2.2.2 id 2 subflow dev eth1
# ip mptcp monitor & [ CREATED] remid=0 locid=0 saddr4=1.1.1.1 daddr4=9.9.9.9 [ ESTABLISHED] remid=0 locid=0 saddr4=1.1.1.1 daddr4=9.9.9.9 [ SF_ESTABLISHED] remid=0 locid=2 saddr4=2.2.2.2 daddr4=9.9.9.9
# ip mptcp endpoint delete id 1 [ SF_CLOSED] remid=0 locid=0 saddr4=1.1.1.1 daddr4=9.9.9.9 [ SF_CLOSED] remid=0 locid=0 saddr4=1.1.1.1 daddr4=9.9.9.9
The first one is coming from mptcp_pm_nl_rm_subflow_received(), and the second one from __mptcp_close_subflow().
To avoid doing the post-closed processing twice, the subflow is now marked as closed the first time.
Note that it is not enough to check if we are dealing with the first subflow and check its sk_state: the subflow might have been reset or closed before calling mptcp_close_ssk().
Fixes: b911c97c7dc7 ("mptcp: add netlink event support") Cc: stable@vger.kernel.org Tested-by: Arınç ÜNAL arinc.unal@arinc9.com Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com [ Conflict in protocol.h due to commit f1f26512a9bf ("mptcp: use plain bool instead of custom binary enum"), commit dfc8d0603033 ("mptcp: implement delayed seq generation for passive fastopen") and more that are not in this version, because they modify the context and the size of __unused. The conflict is easy to resolve, by not only adding the new field (close_event_done), and __unused. ] Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/mptcp/protocol.c | 6 ++++++ net/mptcp/protocol.h | 4 +++- 2 files changed, 9 insertions(+), 1 deletion(-)
--- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2337,6 +2337,12 @@ static void __mptcp_close_ssk(struct soc void mptcp_close_ssk(struct sock *sk, struct sock *ssk, struct mptcp_subflow_context *subflow) { + /* The first subflow can already be closed and still in the list */ + if (subflow->close_event_done) + return; + + subflow->close_event_done = true; + if (sk->sk_state == TCP_ESTABLISHED) mptcp_event(MPTCP_EVENT_SUB_CLOSED, mptcp_sk(sk), ssk, GFP_KERNEL); __mptcp_close_ssk(sk, ssk, subflow); --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -441,7 +441,9 @@ struct mptcp_subflow_context { can_ack : 1, /* only after processing the remote a key */ disposable : 1, /* ctx can be free at ulp release time */ stale : 1, /* unable to snd/rcv data, do not use for xmit */ - valid_csum_seen : 1; /* at least one csum validated */ + valid_csum_seen : 1, /* at least one csum validated */ + close_event_done : 1, /* has done the post-closed part */ + __unused : 11; enum mptcp_data_avail data_avail; u32 remote_nonce; u64 thmac;