netdev - [PATCH net 2/3] sctp: update the netstamp_needed counter when copying sockets

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Date:	Fri,  4 Dec 2015 15:14:04 -0200
From:	Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To:	netdev@...r.kernel.org
Cc:	Vlad Yasevich <vyasevich@...il.com>,
	Neil Horman <nhorman@...driver.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	syzkaller <syzkaller@...glegroups.com>,
	linux-sctp@...r.kernel.org, Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	Maciej Żenczykowski <maze@...gle.com>,
	Dmitry Vyukov <dvyukov@...gle.com>
Subject: [PATCH net 2/3] sctp: update the netstamp_needed counter when copying sockets

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@...gle.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.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 52d27ee924f47867026d8f65c65551a9137219d3..b1d475b5db6825e13df3e3e147fed8654e1cf086 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -740,6 +740,8 @@ 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 e31dfcee1729aa23bdd2ed692fda1b90bd75afb8..d01c8f42dbb2f040fd48009b2767bd4e80aea8ab 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -433,8 +433,6 @@ static bool sock_needs_netstamp(const struct sock *sk)
 	}
 }
 
-#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 03c8256063ec6355fcce034366aa5d005d75b5f7..4c9282bdd06790a0cca7f7c33986e7eb6c541398 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -7199,6 +7199,9 @@ 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,
-- 
2.5.0

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