netdev - Re: Crashes in xfrm

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Message-ID: <20100409092517.GA2645@gondor.apana.org.au>
Date:	Fri, 9 Apr 2010 17:25:17 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Timo Teräs <timo.teras@....fi>
Cc:	broonie@...nsource.wolfsonmicro.com, netdev@...r.kernel.org
Subject: Re: Crashes in xfrm_lookup

On Fri, Apr 09, 2010 at 11:47:12AM +0300, Timo Teräs wrote:
>
> No. Prior it had one element unconditionally. My patch made
> it have zero or one element. The non-SUB_POLICY case crashed
> because xfrm_pols_put(xxx, 0) unconditionally calls
> xfrm_policy_put on unused pointer.

OK I was mistaken.

> __xfrm_lookup(). In the end it uses: "xfrm_pols_put(pols, drop_pols)"
> to free up policies that are looked up with xfrm_sk_policy_lookup().
> The only major code path there is, if per-socket policy has no
> transformations (which is common case, ike daemons do this so they
> can talk IKE without transformations).
>
> If we have cached bundle, the policies are referenced to from the
> bundle and we do not need to reference, or release them in the
> lookup function.
>
> It is a bit icky. But it's the only way to do it, since no one
> wanted to cache per-socket bundles in the flow cache.

BTW, socket policies cannot be sub-policies so you don't need
to expand policies for them.

Cheers,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
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