diff options
| author | Ben McKeegan <ben@netservers.co.uk> | 2009-11-16 03:44:25 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-11-16 23:51:34 -0800 |
| commit | 82b3cc1a2f5e46300a9dec4a8cc8106dc20a4c23 (patch) | |
| tree | 1388b3a52e05a690a1084c06799fb934562901b2 | |
| parent | c0e1f68bce454d244e2eea6b0ab7b3a217c673d2 (diff) | |
ppp: fix BUG on non-linear SKB (multilink receive)
PPP does not correctly call pskb_may_pull() on all necessary receive paths
before reading the PPP protocol, thus causing PPP to report seemingly
random 'unsupported protocols' and eventually trigger BUG_ON(skb->len <
skb->data_len) in skb_pull_rcsum() when receiving multilink protocol in
non-linear skbs.
ppp_receive_nonmp_frame() does not call pskb_may_pull() before reading the
protocol number. For the non-mp receive path this is not a problem, as
this check is done in ppp_receive_frame(). For the mp receive path,
ppp_mp_reconstruct() usually copies the data into a new linear skb.
However, in the case where the frame is made up of a single mp fragment,
the mp header is pulled and the existing skb used. This skb was then
passed to ppp_receive_nonmp_frame() without checking if the encapsulated
protocol header could safely be read.
Signed-off-by: Ben McKeegan <ben@netservers.co.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/net/ppp_generic.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c index 9bf2a6be903..965adb6174c 100644 --- a/drivers/net/ppp_generic.c +++ b/drivers/net/ppp_generic.c @@ -1944,8 +1944,15 @@ ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch) } /* Pull completed packets off the queue and receive them. */ - while ((skb = ppp_mp_reconstruct(ppp))) - ppp_receive_nonmp_frame(ppp, skb); + while ((skb = ppp_mp_reconstruct(ppp))) { + if (pskb_may_pull(skb, 2)) + ppp_receive_nonmp_frame(ppp, skb); + else { + ++ppp->dev->stats.rx_length_errors; + kfree_skb(skb); + ppp_receive_error(ppp); + } + } return; |