From eb70df13ee52dbc0f2c0ffd8ed34a8cd27440baf Mon Sep 17 00:00:00 2001 From: Jarek Poplawski Date: Sun, 10 Jan 2010 22:04:19 +0000 Subject: [PATCH] af_packet: Don't use skb after dev_queue_xmit() tpacket_snd() can change and kfree an skb after dev_queue_xmit(), which is illegal. With debugging by: Stephen Hemminger Reported-by: Michael Breuer With help from: David S. Miller Signed-off-by: Jarek Poplawski Tested-by: Michael Breuer Signed-off-by: David S. Miller --- net/packet/af_packet.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index e0516a2..f126d18 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -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); -- 1.8.2.3