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Commit 4ad19de8 authored by Alexey Kodanev's avatar Alexey Kodanev Committed by David S. Miller
Browse files

net: tcp6: fix double call of tcp_v6_fill_cb() 



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: 2dc49d16 ("tcp6: don't move IP6CB before xfrm6_policy_check()")

Signed-off-by: default avatarAlexey Kodanev <alexey.kodanev@oracle.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2ff2acf1

net/ipv6/tcp_ipv6.c

+11 −0
Original line number Diff line number Diff line
@@ -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 @@ static int tcp_v6_rcv(struct sk_buff *skb) 
			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 @@ static int tcp_v6_rcv(struct sk_buff *skb) 
		tcp_v6_timewait_ack(sk, skb);

		break;

	case TCP_TW_RST:

		tcp_v6_restore_cb(skb);

		goto no_tcp_socket;

	case TCP_TW_SUCCESS:

		;