From: Alexey Kodanev <alexey.kodanev@xxxxxxxxxx>
This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit 4ad19de8774e2a7b075b3e8ea48db85adcf33fa6 ]
tcp_v6_fill_cb() will be called twice if socket's state changes from
TCP_TIME_WAIT to TCP_LISTEN. That can result in control buffer data
corruption because in the second tcp_v6_fill_cb() call it's not copying
IP6CB(skb) anymore, but 'seq', 'end_seq', etc., so we can get weird and
unpredictable results. Performance loss of up to 1200% has been observed
in LTP/vxlan03 test.
This can be fixed by copying inet6_skb_parm to the beginning of 'cb'
only if xfrm6_policy_check() and tcp_v6_fill_cb() are going to be
called again.
Fixes: 2dc49d1680b53 ("tcp6: don't move IP6CB before xfrm6_policy_check()")
Signed-off-by: Alexey Kodanev <alexey.kodanev@xxxxxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
net/ipv6/tcp_ipv6.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 3d60752..79fe5851 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1407,6 +1407,15 @@ static void tcp_v6_fill_cb(struct sk_buff *skb, const struct ipv6hdr *hdr,
TCP_SKB_CB(skb)->sacked = 0;
}
+static void tcp_v6_restore_cb(struct sk_buff *skb)
+{
+ /* We need to move header back to the beginning if xfrm6_policy_check()
+ * and tcp_v6_fill_cb() are going to be called again.
+ */
+ memmove(IP6CB(skb), &TCP_SKB_CB(skb)->header.h6,
+ sizeof(struct inet6_skb_parm));
+}
+
static int tcp_v6_rcv(struct sk_buff *skb)
{
const struct tcphdr *th;
@@ -1539,6 +1548,7 @@ do_time_wait:
inet_twsk_deschedule(tw, &tcp_death_row);
inet_twsk_put(tw);
sk = sk2;
+ tcp_v6_restore_cb(skb);
goto process;
}
/* Fall through to ACK */
@@ -1547,6 +1557,7 @@ do_time_wait:
tcp_v6_timewait_ack(sk, skb);
break;
case TCP_TW_RST:
+ tcp_v6_restore_cb(skb);
goto no_tcp_socket;
case TCP_TW_SUCCESS:
;
--
2.1.0
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