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net: tcp6: fix double call of tcp_v6_fill_cb()

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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: 2dc49d1680 ("tcp6: don't move IP6CB before xfrm6_policy_check()")

Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexey Kodanev 2015-03-27 12:24:22 +03:00 committed by David S. Miller
parent 2ff2acf1fb
commit 4ad19de877
1 changed files with 11 additions and 0 deletions
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11
net/ipv6/tcp_ipv6.c
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@ -1411,6 +1411,15 @@ 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;
@ -1543,6 +1552,7 @@ 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 */
@ -1551,6 +1561,7 @@ 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:
;