From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] Use unsigned variables for packet lengths in ip[6]_queue. Date: Thu, 02 Jun 2011 13:57:42 -0700 (PDT) Message-ID: <20110602.135742.1323883827030625599.davem@davemloft.net> References: <20110420014221.GC26949@redhat.com> <20110419.204105.68144653.davem@davemloft.net> <20110528003651.GA8380@redhat.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, pablo@netfilter.org, kaber@trash.net To: davej@redhat.com Return-path: Received: from shards.monkeyblade.net ([198.137.202.13]:60189 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753682Ab1FBU7z (ORCPT ); Thu, 2 Jun 2011 16:59:55 -0400 In-Reply-To: <20110528003651.GA8380@redhat.com> Sender: netfilter-devel-owner@vger.kernel.org List-ID: From: Dave Jones Date: Fri, 27 May 2011 20:36:51 -0400 > On Tue, Apr 19, 2011 at 08:41:05PM -0700, David Miller wrote: > > From: Dave Jones > > Date: Tue, 19 Apr 2011 21:42:22 -0400 > > > > > Not catastrophic, but ipqueue seems to be too trusting of what it gets > > > passed from userspace, and passes it on down to the page allocator, > > > where it will spew warnings if the page order is too high. > > > > > > __ipq_rcv_skb has several checks for lengths too small, but doesn't > > > seem to have any for oversized ones. I'm not sure what the maximum > > > we should check for is. I'll code up a diff if anyone has any ideas > > > on a sane maximum. > > > > Maybe the thing to do is to simply pass __GFP_NOWARN to nlmsg_new() > > in netlink_ack()? > > > > Anyone else have a better idea? > > So I went back to this today, and found something that doesn't look right. > After adding some instrumentation, and re-running my tests, I found that > the reason we were blowing up with enormous allocations was that we > were passing down a nlmsglen's like -1061109568 > > Is there any reason for that to be signed ? > The nlmsg_len entry of nlmsghdr is a u32, so I'm assuming this is a bug. > > With the patch below, I haven't been able to reproduce the problem, but > I don't know if I've inadvertantly broken some other behaviour somewhere > deeper in netlink where this is valid. netfilter-devel and maintainers CC:'d > -- > > Netlink message lengths can't be negative, so use unsigned variables. > > Signed-off-by: Dave Jones > > diff --git a/net/ipv4/netfilter/ip_queue.c b/net/ipv4/netfilter/ip_queue.c > index d2c1311..f7f9bd7 100644 > --- a/net/ipv4/netfilter/ip_queue.c > +++ b/net/ipv4/netfilter/ip_queue.c > @@ -402,7 +402,8 @@ ipq_dev_drop(int ifindex) > static inline void > __ipq_rcv_skb(struct sk_buff *skb) > { > - int status, type, pid, flags, nlmsglen, skblen; > + int status, type, pid, flags; > + unsigned int nlmsglen, skblen; > struct nlmsghdr *nlh; > > skblen = skb->len; > diff --git a/net/ipv6/netfilter/ip6_queue.c b/net/ipv6/netfilter/ip6_queue.c > index 413ab07..065fe40 100644 > --- a/net/ipv6/netfilter/ip6_queue.c > +++ b/net/ipv6/netfilter/ip6_queue.c > @@ -403,7 +403,8 @@ ipq_dev_drop(int ifindex) > static inline void > __ipq_rcv_skb(struct sk_buff *skb) > { > - int status, type, pid, flags, nlmsglen, skblen; > + int status, type, pid, flags; > + unsigned int nlmsglen, skblen; > struct nlmsghdr *nlh; > > skblen = skb->len;