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sch_teql: should not dereference skb after ndo_start_xmit()
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It is illegal to dereference a skb after a successful ndo_start_xmit()
call. We must store skb length in a local variable instead.

Bug was introduced in 2.6.27 by commit 0abf77e
(net_sched: Add accessor function for packet length for qdiscs)

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Eric Dumazet authored and David S. Miller committed May 18, 2009
1 parent 7752731 commit c0f84d0
Showing 1 changed file with 3 additions and 2 deletions.
5 changes: 3 additions & 2 deletions net/sched/sch_teql.c
Original file line number Diff line number Diff line change
Expand Up @@ -303,15 +303,16 @@ static int teql_master_xmit(struct sk_buff *skb, struct net_device *dev)
switch (teql_resolve(skb, skb_res, slave)) {
case 0:
if (__netif_tx_trylock(slave_txq)) {
unsigned int length = qdisc_pkt_len(skb);

if (!netif_tx_queue_stopped(slave_txq) &&
!netif_tx_queue_frozen(slave_txq) &&
slave_ops->ndo_start_xmit(skb, slave) == 0) {
__netif_tx_unlock(slave_txq);
master->slaves = NEXT_SLAVE(q);
netif_wake_queue(dev);
master->stats.tx_packets++;
master->stats.tx_bytes +=
qdisc_pkt_len(skb);
master->stats.tx_bytes += length;
return 0;
}
__netif_tx_unlock(slave_txq);
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