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af_packet: Don't use skb after dev_queue_xmit()

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tpacket_snd() can change and kfree an skb after dev_queue_xmit(),
which is illegal.

With debugging by: Stephen Hemminger <shemminger@vyatta.com>

Reported-by: Michael Breuer <mbreuer@majjas.com>
With help from: David S. Miller <davem@davemloft.net>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Tested-by: Michael Breuer<mbreuer@majjas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jarek Poplawski 2010-01-10 22:04:19 +00:00 committed by David S. Miller
parent fa15e99b6b
commit eb70df13ee
1 changed files with 14 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
net/packet/af_packet.c
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@ -1021,8 +1021,20 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
status = TP_STATUS_SEND_REQUEST;
err = dev_queue_xmit(skb);
if (unlikely(err > 0 && (err = net_xmit_errno(err)) != 0))
goto out_xmit;
if (unlikely(err > 0)) {
err = net_xmit_errno(err);
if (err && __packet_get_status(po, ph) ==
TP_STATUS_AVAILABLE) {
/* skb was destructed already */
skb = NULL;
goto out_status;
}
/*
* skb was dropped but not destructed yet;
* let's treat it like congestion or err < 0
*/
err = 0;
}
packet_increment_head(&po->tx_ring);
len_sum += tp_len;
} while (likely((ph != NULL) ||
@ -1033,9 +1045,6 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
err = len_sum;
goto out_put;
out_xmit:
skb->destructor = sock_wfree;
atomic_dec(&po->tx_ring.pending);
out_status:
__packet_set_status(po, ph, status);
kfree_skb(skb);