[patch 05/87] sch_teql: should not dereference skb after ndo_start_xmit()

Greg KH
2009-06-09T10:16:31Z

[-- Attachment #1: sch_teql-should-not-dereference-skb-after-ndo_start_xmit.patch --]
[-- Type: text/plain, Size: 1394 bytes --]

2.6.29-stable review patch. If anyone has any objections, please let us know.

------------------

From: Eric Dumazet <dada1@cosmosbay.com>

[ Upstream commit c0f84d0d4be3f7d818b4ffb04d27f9bae64397f0 ]

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 0abf77e55a2459aa9905be4b226e4729d5b4f0cb
(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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
net/sched/sch_teql.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/net/sched/sch_teql.c
+++ b/net/sched/sch_teql.c
@@ -303,6 +303,8 @@ restart:
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) {
@@ -310,8 +312,7 @@ restart:
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);