From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Ricardo Leitner Subject: Re: [PATCH net v2] sctp: asconf's process should verify address parameter is in the beginning Date: Tue, 25 Aug 2015 11:01:13 -0300 Message-ID: <20150825140113.GD1873@localhost.localdomain> References: <3ffe8f6b86e33c016dddec672fab23a206c21acf.1440505764.git.lucien.xin@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: network dev , davem@davemloft.net, vyasevic@redhat.com To: Xin Long Return-path: Received: from mx1.redhat.com ([209.132.183.28]:52846 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752418AbbHYOBQ (ORCPT ); Tue, 25 Aug 2015 10:01:16 -0400 Content-Disposition: inline In-Reply-To: <3ffe8f6b86e33c016dddec672fab23a206c21acf.1440505764.git.lucien.xin@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Aug 25, 2015 at 08:29:24PM +0800, 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. > > v1->v2: > * put the check behind the params' length verify. > > Signed-off-by: Xin Long > --- > net/sctp/sm_make_chunk.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c > index 06320c8..89a4d1c 100644 > --- a/net/sctp/sm_make_chunk.c > +++ b/net/sctp/sm_make_chunk.c > @@ -3166,6 +3166,13 @@ bool sctp_verify_asconf(const struct sctp_association *asoc, > return false; > if (!addr_param_needed && addr_param_seen) > return false; > + if (addr_param_needed && addr_param_seen) { > + /* Ensure the address parameter is in the beginning */ > + param.v = chunk->skb->data + sizeof(sctp_addiphdr_t); Using param.v before the loop made sense but after the loop, it will cause all packets that hits here to be reject due to the check below. > + if (param.p->type != SCTP_PARAM_IPV4_ADDRESS && > + param.p->type != SCTP_PARAM_IPV6_ADDRESS) > + return false; > + } > if (param.v != chunk->chunk_end) this one -----^ Maybe it's easier if you put this check inside the loop for each ipv4/6, and check if it is the first parameter or not by mimicing the way sctp_walk_params() finds the first chunk, it's just a pointer derreference and that was already checked and performed to reach there. (You can have some logic with addr_param_seen so you don't catch the multiple parameters in there.) Marcelo > return false; > > -- > 2.1.0 >