linux-kernel - Re: IPv4: ip_options_compile() how can we avoid blowing up on a NULL skb???

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Message-Id: <E1GkrUv-00043G-00@gondolin.me.apana.org.au>
Date:	Fri, 17 Nov 2006 11:22:25 +1100
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	jesper.juhl@...il.com (Jesper Juhl)
Cc:	netdev@...r.kernel.org, davem@...emloft.net,
	linux-kernel@...r.kernel.org
Subject: Re: IPv4: ip_options_compile() how can we avoid blowing up on a NULL skb???

Jesper Juhl <jesper.juhl@...il.com> wrote:
> 
> So if 'skb' is NULL, the only route I see that doesn't cause a NULL
> pointer deref is if  (opt != NULL)  and at the same time
> (opt->is_data != NULL)  .   Is that guaranteed in any way?  If now,
> how come we don't blow up regularly?

Yes that's how it's supposed to be used.  This function either constructs
an opts structure from a packet, or it verifies the validity of a suspect
opts structure (without a packet).  In the latter case, both opt and
opt->is_data should be non-zero.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
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