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[PATCH 4.9 24/78] sctp: fix missing wake ups in some situations

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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>


[ Upstream commit 7906b00f5cd1cd484fced7fcda892176e3202c8a ]

Commit fb586f25300f ("sctp: delay calls to sk_data_ready() as much as
possible") minimized the number of wake ups that are triggered in case
the association receives a packet with multiple data chunks on it and/or
when io_events are enabled and then commit 0970f5b36659 ("sctp: signal
sk_data_ready earlier on data chunks reception") moved the wake up to as
soon as possible. It thus relies on the state machine running later to
clean the flag that the event was already generated.

The issue is that there are 2 call paths that calls
sctp_ulpq_tail_event() outside of the state machine, causing the flag to
linger and possibly omitting a needed wake up in the sequence.

One of the call paths is when enabling SCTP_SENDER_DRY_EVENTS via
setsockopt(SCTP_EVENTS), as noticed by Harald Welte. The other is when
partial reliability triggers removal of chunks from the send queue when
the application calls sendmsg().

This commit fixes it by not setting the flag in case the socket is not
owned by the user, as it won't be cleaned later. This works for
user-initiated calls and also for rx path processing.

Fixes: fb586f25300f ("sctp: delay calls to sk_data_ready() as much as possible")
Reported-by: Harald Welte <laforge@gnumonks.org>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/sctp/ulpqueue.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/sctp/ulpqueue.c
+++ b/net/sctp/ulpqueue.c
@@ -265,7 +265,8 @@ int sctp_ulpq_tail_event(struct sctp_ulp
 		sctp_ulpq_clear_pd(ulpq);
 
 	if (queue == &sk->sk_receive_queue && !sp->data_ready_signalled) {
-		sp->data_ready_signalled = 1;
+		if (!sock_owned_by_user(sk))
+			sp->data_ready_signalled = 1;
 		sk->sk_data_ready(sk);
 	}
 	return 1;

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[PATCH 4.9 00/78] 4.9.51-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 19/78] gianfar: Fix Tx flow control deactivation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 03/78] ipv6: fix sparse warning on rt6i_node Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 05/78] udp: on peeking bad csum, drop packets even if not at head Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 31/78] xfs: Move handling of missing page into one place in xfs_find_get_desired_pgoff() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 26/78] f2fs: let fill_super handle roll-forward errors Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 23/78] ipv6: fix typo in fib6_net_exit() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 20/78] vhost_net: correctly check tx avail during rx busy polling Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 10/78] cxgb4: Fix stack out-of-bounds read due to wrong size to t4_record_mbox() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 44/78] xfs: fix quotacheck dquot id overflow infinite loop Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 42/78] xfs: set firstfsb to NULLFSBLOCK before feeding it to _bmapi_write Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 21/78] ip6_gre: update mtu properly in ip6gre_err Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 13/78] Revert "net: phy: Correctly process PHY_HALTED in phy_stop_machine()" Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 14/78] tcp: initialize rcv_mss to TCP_MIN_MSS instead of 0 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 22/78] ipv6: fix memory leak with multiple tables during netns destruction Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 17/78] Revert "net: use lib/percpu_counter API for fragmentation mem accounting" Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 24/78] sctp: fix missing wake ups in some situations Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 28/78] x86/fsgsbase/64: Fully initialize FS and GS state in start_thread_common Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 15/78] mlxsw: spectrum: Forbid linking to devices that have uppers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.9 06/78] fsl/man: Inherit parent device and of_node Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  Re: [PATCH 4.9 00/78] 4.9.51-stable review Tom Gall <tom.gall@linaro.org> - 2017-09-18 14:30 +0200
    Re: [PATCH 4.9 00/78] 4.9.51-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 16:30 +0200
  Re: [PATCH 4.9 00/78] 4.9.51-stable review Guenter Roeck <linux@roeck-us.net> - 2017-09-18 21:30 +0200
    Re: [PATCH 4.9 00/78] 4.9.51-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-19 08:40 +0200
  Re: [PATCH 4.9 00/78] 4.9.51-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-09-18 22:00 +0200

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