linux-kernel - Re: [PATCH] OMAP: Dereference of NULL autodep in _autodep

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Message-ID: <25e057c01002241424s71cc447di4cb93de895cb665b@mail.gmail.com>
Date:	Wed, 24 Feb 2010 23:24:23 +0100
From:	roel kluin <roel.kluin@...il.com>
To:	Paul Walmsley <paul@...an.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-omap@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] OMAP: Dereference of NULL autodep in _autodep_lookup()

> Thanks for the patch, but I don't understand what problem you're
> pointing out.  If autodeps is NULL entering clkdm_init(), then the
> for-loop won't even be entered.

My first patch was wrong, but there's something I think could
be wrong. In clkdm_init() we have:

for (autodep = autodeps; autodep->pwrdm.ptr; autodep++)
        _autodep_lookup(autodep);

In _autodep_lookup() we ensure that we don't dereference
autodep by:

if (!autodep)
        return;

but if autodep can be NULL we already dereferenced it in
the aforementioned for loop, so shouldn't that be:

for (autodep = autodeps; autodep && autodep->pwrdm.ptr; autodep++)
        _autodep_lookup(autodep);

Then since this is the only call to _autodep_lookup() we can remove
that test there. Do you agree?

> It looks like there may be a problem, however, in _clkdm_add_autodeps()
> and _clkdm_del_autodeps() if no autodeps were passed in.  What do you
> think about something like the following instead?
>
>
> - Paul

Your suggested patch looks right to me as well.
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