From d80caeb9b86d2c8116776953ae3e3c0ddda364f1 Mon Sep 17 00:00:00 2001
From: Alexander Potapenko <glider@google.com>
Date: Tue, 21 Mar 2017 17:14:27 +0100
Subject: ipv6: make sure to initialize sockc.tsflags before first use

[ Upstream commit d515684d78148884d5fc425ba904c50f03844020 ]

In the case udp_sk(sk)->pending is AF_INET6, udpv6_sendmsg() would
jump to do_append_data, skipping the initialization of sockc.tsflags.
Fix the problem by moving sockc.tsflags initialization earlier.

The bug was detected with KMSAN.

Fixes: c14ac9451c34 ("sock: enable timestamping using control messages")
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index e4a8000..40a289f 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1037,6 +1037,7 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	ipc6.hlimit = -1;
 	ipc6.tclass = -1;
 	ipc6.dontfrag = -1;
+	sockc.tsflags = sk->sk_tsflags;
 
 	/* destination address check */
 	if (sin6) {
@@ -1156,7 +1157,6 @@ do_udp_sendmsg:
 		fl6.flowi6_oif = np->sticky_pktinfo.ipi6_ifindex;
 
 	fl6.flowi6_mark = sk->sk_mark;
-	sockc.tsflags = sk->sk_tsflags;
 
 	if (msg->msg_controllen) {
 		opt = &opt_space;
-- 
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