Re: [PATCH] netfilter: nf_tables: fix loop checking with set element data

[Patrick McHardy <kaber@trash.net>]

On Fri, Feb 07, 2014 at 03:47:34PM +0000, Patrick McHardy wrote:
> On Fri, Feb 07, 2014 at 04:23:51PM +0100, Pablo Neira Ayuso wrote:
> > This patch fixes two bugs:
> > 
> > * Restrict the validation to verdict maps only, since struct nft_data
> >   is declared as a union, data[0] may contain the values -3 or -4 which
> >   match with NFT_JUMP and NFT_GOTO. I think this will result in crash
> >   while performing the chain loop validation.
> > 
> > * Access to uninitialized data for end interval elements. The element
> >   data part is uninitialized in interval end elements.
> > 
> 
> That's not necessary. The function is only invoked for NFT_DATA_VERDICT.
> 
> 
> > Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> > ---
> >  net/netfilter/nf_tables_api.c |    5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
> > index d0c790e3e..522becb 100644
> > --- a/net/netfilter/nf_tables_api.c
> > +++ b/net/netfilter/nf_tables_api.c
> > @@ -2998,6 +2998,11 @@ static int nf_tables_loop_check_setelem(const struct nft_ctx *ctx,
> >  					const struct nft_set_iter *iter,
> >  					const struct nft_set_elem *elem)
> >  {
> > +	if (!(set->flags & NFT_SET_MAP) ||
> > +	    set->dtype != NFT_DATA_VERDICT ||
> > +	    elem->flags & NFT_SET_ELEM_INTERVAL_END)
> > +		return 0;
> > +

Right, I get the intention now.

This function is only called for maps with dtype verdict, so just the check
for SET_ELEM_INTERVAL_END is all we need.

> >  	switch (elem->data.verdict) {
> >  	case NFT_JUMP:
> >  	case NFT_GOTO:
> > -- 
> > 1.7.10.4
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