[3.19.y-ckt stable] Patch "sctp: update the netstamp_needed counter when copying sockets" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    sctp: update the netstamp_needed counter when copying sockets

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt13.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From e49b046eeb7bd8fe6ea9a8c0533625e32dce5759 Mon Sep 17 00:00:00 2001
From: Marcelo Ricardo Leitner <marcelo.leitner at gmail.com>
Date: Fri, 4 Dec 2015 15:14:04 -0200
Subject: sctp: update the netstamp_needed counter when copying sockets

[ Upstream commit 01ce63c90170283a9855d1db4fe81934dddce648 ]

Dmitry Vyukov reported that SCTP was triggering a WARN on socket destroy
related to disabling sock timestamp.

When SCTP accepts an association or peel one off, it copies sock flags
but forgot to call net_enable_timestamp() if a packet timestamping flag
was copied, leading to extra calls to net_disable_timestamp() whenever
such clones were closed.

The fix is to call net_enable_timestamp() whenever we copy a sock with
that flag on, like tcp does.

Reported-by: Dmitry Vyukov <dvyukov at google.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner at gmail.com>
Acked-by: Vlad Yasevich <vyasevich at gmail.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 include/net/sock.h | 2 ++
 net/core/sock.c    | 2 --
 net/sctp/socket.c  | 3 +++
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 173743e..6690502 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -721,6 +721,8 @@ enum sock_flags {
 	SOCK_SELECT_ERR_QUEUE, /* Wake select on error queue */
 };

+#define SK_FLAGS_TIMESTAMP ((1UL << SOCK_TIMESTAMP) | (1UL << SOCK_TIMESTAMPING_RX_SOFTWARE))
+
 static inline void sock_copy_flags(struct sock *nsk, struct sock *osk)
 {
 	nsk->sk_flags = osk->sk_flags;
diff --git a/net/core/sock.c b/net/core/sock.c
index 3606cc5..4367761 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -422,8 +422,6 @@ static void sock_warn_obsolete_bsdism(const char *name)
 	}
 }

-#define SK_FLAGS_TIMESTAMP ((1UL << SOCK_TIMESTAMP) | (1UL << SOCK_TIMESTAMPING_RX_SOFTWARE))
-
 static void sock_disable_timestamp(struct sock *sk, unsigned long flags)
 {
 	if (sk->sk_flags & flags) {
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 4e56571..ef43246 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -7214,6 +7214,9 @@ void sctp_copy_sock(struct sock *newsk, struct sock *sk,
 	newinet->mc_ttl = 1;
 	newinet->mc_index = 0;
 	newinet->mc_list = NULL;
+
+	if (newsk->sk_flags & SK_FLAGS_TIMESTAMP)
+		net_enable_timestamp();
 }

 static inline void sctp_copy_descendant(struct sock *sk_to,
--
1.9.1