From: Florian Westphal <fw@strlen.de>
To: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Florian Westphal <fw@strlen.de>, netfilter-devel@vger.kernel.org
Subject: Re: [PATCH] netfilter: nft_compat: check match/targetinfo attr size
Date: Thu, 10 Mar 2016 18:00:01 +0100 [thread overview]
Message-ID: <20160310170001.GC14718@breakpoint.cc> (raw)
In-Reply-To: <20160310164710.GA3267@salvia>
Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> On Wed, Mar 09, 2016 at 12:04:21AM +0100, Florian Westphal wrote:
> > We copy accoring to ->target|matchsize, so check that the netlink attribute
> > (which can include padding and might be larger) contains enough data.
> >
> > Reported-by: Julia Lawall <Julia.Lawall@lip6.fr>
> > Signed-off-by: Florian Westphal <fw@strlen.de>
>
> I think xt_check_match() and xt_check_target() already validate this
> for us.
But AFAICS we copy before this:
nft_target_init:
size = XT_ALIGN(nla_len(tb[NFTA_TARGET_INFO]));
...
target_compat_from_user(target, nla_data(tb[NFTA_TARGET_INFO]), info);
-> memcpy(out, in, t->targetsize);
xt_check_target(&par, size, proto, inv); // checks size vs. targetsize
'target' is sized based on target->targetsize in
nft_target_select_ops().
So if tb[NFTA_TARGET_INFO] is != t->targetsize we might copy more
data than whats in 'in', no?
next prev parent reply other threads:[~2016-03-10 17:00 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-08 23:04 [PATCH] netfilter: nft_compat: check match/targetinfo attr size Florian Westphal
2016-03-10 16:47 ` Pablo Neira Ayuso
2016-03-10 17:00 ` Florian Westphal [this message]
2016-03-10 17:16 ` Pablo Neira Ayuso
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