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authorBen McKeegan <ben@netservers.co.uk>2009-11-15 22:44:25 -0500
committerDavid S. Miller <davem@davemloft.net>2009-11-17 02:51:34 -0500
commit82b3cc1a2f5e46300a9dec4a8cc8106dc20a4c23 (patch)
tree1388b3a52e05a690a1084c06799fb934562901b2 /drivers/net
parentc0e1f68bce454d244e2eea6b0ab7b3a217c673d2 (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>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/ppp_generic.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c
index 9bf2a6be9031..965adb6174c3 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)
1944 } 1944 }
1945 1945
1946 /* Pull completed packets off the queue and receive them. */ 1946 /* Pull completed packets off the queue and receive them. */
1947 while ((skb = ppp_mp_reconstruct(ppp))) 1947 while ((skb = ppp_mp_reconstruct(ppp))) {
1948 ppp_receive_nonmp_frame(ppp, skb); 1948 if (pskb_may_pull(skb, 2))
1949 ppp_receive_nonmp_frame(ppp, skb);
1950 else {
1951 ++ppp->dev->stats.rx_length_errors;
1952 kfree_skb(skb);
1953 ppp_receive_error(ppp);
1954 }
1955 }
1949 1956
1950 return; 1957 return;
1951 1958