From: Ben McKeegan <ben@xxxxxxxxxxxxxxxx>
Date: Mon, 16 Nov 2009 13:44:25 +0000 (GMT)
> 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@xxxxxxxxxxxxxxxx>
Applied but:
> + while ((skb = ppp_mp_reconstruct(ppp))) {
> + if (pskb_may_pull(skb, 2))
There is a mix of space and tab characters leading up to
the "if (pskb_may_pull" there, I fixed it up but please
take care of such trivial issues before submitting your
patch next time.
Thanks.
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