Looking at current situation of memory management in 6lowpan receive function I detected some invalid handling. After calling lowpan_invoke_rx_handlers we will do a kfree_skb and then NET_RX_DROP on error handling. We don't do this before, also on skb_share_check/skb_unshare which might manipulate the reference counters. After running some 'grep -r "dev_add_pack" net/' to look how others packet-layer receive callbacks works I detected that every subsystem do a kfree_skb, then NET_RX_DROP without calling skb functions which might manipulate the skb reference counters. This is the reason why we should do the same here like all others subsystems. I didn't find any documentation how the packet-layer receive callbacks handle NET_RX_DROP return values either. This patch will add a kfree_skb, then NET_RX_DROP handling for the "trivial checks", in case of skb_share_check/skb_unshare the kfree_skb call will be done inside these functions. Signed-off-by: Alexander Aring <alex.aring@xxxxxxxxx> --- References how other filesystem handle the callback: [0] http://lxr.free-electrons.com/source/net/ipx/af_ipx.c#L1638 [1] http://lxr.free-electrons.com/source/net/can/af_can.c#L709 [2] http://lxr.free-electrons.com/source/net/phonet/af_phonet.c#L371 net/ieee802154/6lowpan/rx.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/net/ieee802154/6lowpan/rx.c b/net/ieee802154/6lowpan/rx.c index 403f171..ef185dd 100644 --- a/net/ieee802154/6lowpan/rx.c +++ b/net/ieee802154/6lowpan/rx.c @@ -284,16 +284,16 @@ static int lowpan_rcv(struct sk_buff *skb, struct net_device *wdev, if (wdev->type != ARPHRD_IEEE802154 || skb->pkt_type == PACKET_OTHERHOST || !lowpan_rx_h_check(skb)) - return NET_RX_DROP; + goto drop; ldev = wdev->ieee802154_ptr->lowpan_dev; if (!ldev || !netif_running(ldev)) - return NET_RX_DROP; + goto drop; /* Replacing skb->dev and followed rx handlers will manipulate skb. */ skb = skb_share_check(skb, GFP_ATOMIC); if (!skb) - return NET_RX_DROP; + goto out; skb->dev = ldev; /* When receive frag1 it's likely that we manipulate the buffer. @@ -304,10 +304,15 @@ static int lowpan_rcv(struct sk_buff *skb, struct net_device *wdev, lowpan_is_iphc(*skb_network_header(skb))) { skb = skb_unshare(skb, GFP_ATOMIC); if (!skb) - return NET_RX_DROP; + goto out; } return lowpan_invoke_rx_handlers(skb); + +drop: + kfree_skb(skb); +out: + return NET_RX_DROP; } static struct packet_type lowpan_packet_type = { -- 2.6.1 -- To unsubscribe from this list: send the line "unsubscribe linux-wpan" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
