Hi Marcelo, I can confirm that your patch fixes the issue for me.
Tested-by: Andrey Konovalov <andreyk...@google.com> On Mon, Oct 24, 2016 at 9:44 PM, Marcelo Ricardo Leitner <marcelo.leit...@gmail.com> wrote: > Hi Andrey, > > On Mon, Oct 24, 2016 at 05:30:04PM +0200, Andrey Konovalov wrote: >> The problem is that sctp_walk_errors walks the chunk before its length >> is checked for overflow. > > Exactly. The check is done too late, for the 2nd and subsequent chunks > only. > Please try the following patch, thanks. Note: not even compile tested. > > ---8<--- > > diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c > index 026e3bca4a94..8ec20a64a3f8 100644 > --- a/net/sctp/sm_statefuns.c > +++ b/net/sctp/sm_statefuns.c > @@ -3422,6 +3422,12 @@ sctp_disposition_t sctp_sf_ootb(struct net *net, > return sctp_sf_violation_chunklen(net, ep, asoc, > type, arg, > commands); > > + /* Report violation if chunk len overflows */ > + ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length)); > + if (ch_end > skb_tail_pointer(skb)) > + return sctp_sf_violation_chunklen(net, ep, asoc, > type, arg, > + commands); > + > /* Now that we know we at least have a chunk header, > * do things that are type appropriate. > */ > @@ -3453,12 +3459,6 @@ sctp_disposition_t sctp_sf_ootb(struct net *net, > } > } > > - /* Report violation if chunk len overflows */ > - ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length)); > - if (ch_end > skb_tail_pointer(skb)) > - return sctp_sf_violation_chunklen(net, ep, asoc, > type, arg, > - commands); > - > ch = (sctp_chunkhdr_t *) ch_end; > } while (ch_end < skb_tail_pointer(skb)); >
