[PATCH 4.0 009/105] tcp/ipv6: fix flow label setting in TIME_WAIT state

[Greg Kroah-Hartman]

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

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

From: Florent Fourcot <florent.fourcot@xxxxxxxxxxxxxxxx>

[ Upstream commit 21858cd02dabcf290564cbf4769b101eba54d7bb ]

commit 1d13a96c74fc ("ipv6: tcp: fix flowlabel value in ACK messages
send from TIME_WAIT") added the flow label in the last TCP packets.
Unfortunately, it was not casted properly.

This patch replace the buggy shift with be32_to_cpu/cpu_to_be32.

Fixes: 1d13a96c74fc ("ipv6: tcp: fix flowlabel value in ACK messages")
Reported-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Signed-off-by: Florent Fourcot <florent.fourcot@xxxxxxxxxxxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/ipv4/tcp_minisocks.c |    2 +-
 net/ipv6/tcp_ipv6.c      |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -316,7 +316,7 @@ void tcp_time_wait(struct sock *sk, int
 			tw->tw_v6_daddr = sk->sk_v6_daddr;
 			tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 			tw->tw_tclass = np->tclass;
-			tw->tw_flowlabel = np->flow_label >> 12;
+			tw->tw_flowlabel = be32_to_cpu(np->flow_label & IPV6_FLOWLABEL_MASK);
 			tw->tw_ipv6only = sk->sk_ipv6only;
 		}
 #endif
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -975,7 +975,7 @@ static void tcp_v6_timewait_ack(struct s
 			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
 			tcp_time_stamp + tcptw->tw_ts_offset,
 			tcptw->tw_ts_recent, tw->tw_bound_dev_if, tcp_twsk_md5_key(tcptw),
-			tw->tw_tclass, (tw->tw_flowlabel << 12));
+			tw->tw_tclass, cpu_to_be32(tw->tw_flowlabel));
 
 	inet_twsk_put(tw);
 }


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