netdev - Re: Kernel memory corruption in CIPSO labeled TCP packets processing.

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Date:   Tue, 22 Jan 2019 12:48:04 -0500
From:   Paul Moore <paul@...l-moore.com>
To:     Nazarov Sergey <s-nazarov@...dex.ru>
Cc:     "linux-security-module@...r.kernel.org" 
        <linux-security-module@...r.kernel.org>,
        "selinux@...r.kernel.org" <selinux@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Casey Schaufler <casey@...aufler-ca.com>
Subject: Re: Kernel memory corruption in CIPSO labeled TCP packets processing.

On Tue, Jan 22, 2019 at 12:35 PM Nazarov Sergey <s-nazarov@...dex.ru> wrote:
> 22.01.2019, 19:49, "Paul Moore" <paul@...l-moore.com>:
> >
> > Granted I'm looking at this rather quickly, so I may be missing
> > something, but why the changes to ip_options_compile()? Couldn't you
> > simply set opt->data manually (set the ptr) in cipso_v4_error() before
> > calling ip_options_compile() and arrive at the same result without
> > having to modify ip_options_compile()? I suppose there is the rtable
> > value to worry about, but ip_options_echo() should take care of that,
> > yes? No?
>
> ip_options_compile calls icmp_send, if someting wrong. So, we'll go back
> to trying to fix. ip_options_compile changes needed to avoid this.

Yes, exactly.  If you don't pass the skb it shouldn't attempt to call
icmp_send() in case of error.

-- 
paul moore
www.paul-moore.com