From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Yasevich Subject: Re: [PATCH net] sctp: asconf's process should verify address parameter is in the beginning Date: Mon, 24 Aug 2015 13:33:48 -0400 Message-ID: <55DB557C.6090506@redhat.com> References: <87d339ea910a3665c9376b6ba69b003af967c6d1.1440410878.git.lucien.xin@gmail.com> Reply-To: vyasevic@redhat.com Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: mleitner@redhat.com, davem@davemloft.net To: Xin Long , network dev Return-path: Received: from mx1.redhat.com ([209.132.183.28]:39431 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932242AbbHXRdv (ORCPT ); Mon, 24 Aug 2015 13:33:51 -0400 In-Reply-To: <87d339ea910a3665c9376b6ba69b003af967c6d1.1440410878.git.lucien.xin@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: On 08/24/2015 06:07 AM, Xin Long wrote: > in sctp_process_asconf(), we get address parameter from the beginning of the > addip params. but we never check if it's really there. if the addr param is not > there, it still can pass sctp_verify_asconf(), then to be handled by > sctp_process_asconf(), it will not be safe. > > so add a code in sctp_verify_asconf() to check the address parameter is in the > beginning, or return false to send abort. > > Signed-off-by: Xin Long > --- > net/sctp/sm_make_chunk.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c > index 0ee5ca7..a2a72d5 100644 > --- a/net/sctp/sm_make_chunk.c > +++ b/net/sctp/sm_make_chunk.c > @@ -3122,6 +3122,14 @@ bool sctp_verify_asconf(const struct sctp_association *asoc, > union sctp_params param; > bool addr_param_seen = false; > > + if(addr_param_needed){ > + /* Ensure the address parameter is in the beginning */ > + param.v = chunk->skb->data + sizeof(sctp_addiphdr_t); > + if (param.p->type != SCTP_PARAM_IPV4_ADDRESS && > + param.p->type != SCTP_PARAM_IPV6_ADDRESS) > + return false; > + } > + Sorry, you can't do that directly without a lot more checks. The parameer may be only only partial, or may not be there at all. You'd end up looking at wrong mememory. A better way would be to set the addr_param_seen only when looking at the first parameter (addip_hdr.params). -vlad > sctp_walk_params(param, addip, addip_hdr.params) { > size_t length = ntohs(param.p->length); > >