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Date: Thu, 12 May 2016 11:15:24 -0500 From: ebiederm@...ssion.com (Eric W. Biederman) To: Pablo Neira Ayuso <pablo@...filter.org> Cc: Florian Westphal <fw@...len.de>, netfilter-devel@...r.kernel.org, dale.4d@...il.com, netdev@...r.kernel.org Subject: Re: [PATCH nf V2] netfilter: fix oops in nfqueue during netns error unwinding Pablo Neira Ayuso <pablo@...filter.org> writes: > On Wed, May 11, 2016 at 05:41:13PM +0200, Florian Westphal wrote: >> diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c >> index 5baa8e2..9722819 100644 >> --- a/net/netfilter/nf_queue.c >> +++ b/net/netfilter/nf_queue.c >> @@ -102,6 +102,13 @@ void nf_queue_nf_hook_drop(struct net *net, struct nf_hook_ops *ops) >> { >> const struct nf_queue_handler *qh; >> >> + /* netns wasn't initialized, error unwind in progress. >> + * Its possible that the nfq netns init function was not even >> + * called, in which case nfq pernetns data is in undefined state. >> + */ >> + if (!net->list.next) >> + return; > > Thanks Florian. > > Question for the netns folks: Is this a stable assumption? My only > concern with this is that it relies on internal the netns > representation, so I'd like to make sure this thing doesn't break > again. > > Let me know, thanks. Ugh. I got distracted before I finished replying. I don't think the analysis is correct. The unwind and the netns exit path should maintain the same constraints. If they don't there is a bug, perhaps in initialization ordering. Code should be able to count on net_generic() from the beginning of the corresponding .init to the end of the corresponding .fini Something like that is not happening and if we can I would like to track down why. Otherwise we need code like the above all over the place. Eric
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