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[TCP]: Fix never pruned tcp out-of-order queue. 

tcp_prune_queue() doesn't prune an out-of-order queue at all.
Therefore sk_rmem_schedule() can fail but the out-of-order queue isn't
pruned . This can lead to tcp deadlock state if the next two
conditions are held:

1. There are a sequence hole between last received in
   order segment and segments enqueued to the out-of-order queue.

2. Size of all segments in the out-of-order queue is more than tcp_mem[2].

Signed-off-by: Vitaliy Gusev <vgusev@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vitaliy Gusev 2008-04-15 00:33:38 -07:00 committed by David S. Miller
parent 066a3b5b23
commit b000cd3707
1 changed files with 46 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

72
net/ipv4/tcp_input.c
View File

@ -3841,8 +3841,26 @@ static void tcp_ofo_queue(struct sock *sk)
}
}
static void tcp_prune_ofo_queue(struct sock *sk);
static int tcp_prune_queue(struct sock *sk);
static inline int tcp_try_rmem_schedule(struct sock *sk, unsigned int size)
{
if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
!sk_rmem_schedule(sk, size)) {
if (tcp_prune_queue(sk) < 0)
return -1;
if (!sk_rmem_schedule(sk, size)) {
tcp_prune_ofo_queue(sk);
if (!sk_rmem_schedule(sk, size))
return -1;
}
}
return 0;
}
static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
{
struct tcphdr *th = tcp_hdr(skb);
@ -3892,12 +3910,9 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
if (eaten <= 0) {
queue_and_out:
if (eaten < 0 &&
(atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
!sk_rmem_schedule(sk, skb->truesize))) {
if (tcp_prune_queue(sk) < 0 ||
!sk_rmem_schedule(sk, skb->truesize))
goto drop;
}
tcp_try_rmem_schedule(sk, skb->truesize))
goto drop;
skb_set_owner_r(skb, sk);
__skb_queue_tail(&sk->sk_receive_queue, skb);
}
@ -3966,12 +3981,8 @@ drop:
TCP_ECN_check_ce(tp, skb);
if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
!sk_rmem_schedule(sk, skb->truesize)) {
if (tcp_prune_queue(sk) < 0 ||
!sk_rmem_schedule(sk, skb->truesize))
goto drop;
}
if (tcp_try_rmem_schedule(sk, skb->truesize))
goto drop;
/* Disable header prediction. */
tp->pred_flags = 0;
@ -4198,6 +4209,28 @@ static void tcp_collapse_ofo_queue(struct sock *sk)
}
}
/*
* Purge the out-of-order queue.
*/
static void tcp_prune_ofo_queue(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
if (!skb_queue_empty(&tp->out_of_order_queue)) {
NET_INC_STATS_BH(LINUX_MIB_OFOPRUNED);
__skb_queue_purge(&tp->out_of_order_queue);
/* Reset SACK state. A conforming SACK implementation will
* do the same at a timeout based retransmit. When a connection
* is in a sad state like this, we care only about integrity
* of the connection not performance.
*/
if (tp->rx_opt.sack_ok)
tcp_sack_reset(&tp->rx_opt);
sk_mem_reclaim(sk);
}
}
/* Reduce allocated memory if we can, trying to get
* the socket within its memory limits again.
*
@ -4231,20 +4264,7 @@ static int tcp_prune_queue(struct sock *sk)
/* Collapsing did not help, destructive actions follow.
* This must not ever occur. */
/* First, purge the out_of_order queue. */
if (!skb_queue_empty(&tp->out_of_order_queue)) {
NET_INC_STATS_BH(LINUX_MIB_OFOPRUNED);
__skb_queue_purge(&tp->out_of_order_queue);
/* Reset SACK state. A conforming SACK implementation will
* do the same at a timeout based retransmit. When a connection
* is in a sad state like this, we care only about integrity
* of the connection not performance.
*/
if (tcp_is_sack(tp))
tcp_sack_reset(&tp->rx_opt);
sk_mem_reclaim(sk);
}
tcp_prune_ofo_queue(sk);
if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf)
return 0;