From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965769AbcJYMdq (ORCPT ); Tue, 25 Oct 2016 08:33:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47936 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932254AbcJYMdo (ORCPT ); Tue, 25 Oct 2016 08:33:44 -0400 Date: Tue, 25 Oct 2016 10:33:39 -0200 From: Marcelo Ricardo Leitner To: Andrey Konovalov Cc: Vlad Yasevich , Neil Horman , "David S. Miller" , linux-sctp@vger.kernel.org, netdev , LKML , syzkaller , Kostya Serebryany , Alexander Potapenko , Eric Dumazet , Dmitry Vyukov Subject: Re: net/sctp: slab-out-of-bounds in sctp_sf_ootb Message-ID: <20161025123339.GA4193@localhost.localdomain> References: <20161024194422.GF2958@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.7.1 (2016-10-04) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Tue, 25 Oct 2016 12:33:44 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 25, 2016 at 02:23:48PM +0200, Andrey Konovalov wrote: > Hi Marcelo, > > I can confirm that your patch fixes the issue for me. > > Tested-by: Andrey Konovalov Great, thanks Andrey! I'll post the patch in a few. > > On Mon, Oct 24, 2016 at 9:44 PM, Marcelo Ricardo Leitner > 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)); > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-sctp" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >