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ieee802154: 6lowpan: fix memory leak 

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@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This commit is contained in:
Alexander Aring 2015-10-22 12:11:27 +02:00 committed by Marcel Holtmann
parent 88d07feb09
commit aeedebff69
1 changed files with 9 additions and 4 deletions
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13
net/ieee802154/6lowpan/rx.c
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@ -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 = {