From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Jones Subject: [PATCH] Use unsigned variables for packet lengths in ip[6]_queue. Date: Fri, 27 May 2011 20:36:51 -0400 Message-ID: <20110528003651.GA8380@redhat.com> References: <20110420014221.GC26949@redhat.com> <20110419.204105.68144653.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org To: David Miller Return-path: Received: from mx1.redhat.com ([209.132.183.28]:48321 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757560Ab1E1Agz (ORCPT ); Fri, 27 May 2011 20:36:55 -0400 Content-Disposition: inline In-Reply-To: <20110419.204105.68144653.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: 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. Dave -- 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;