linux-kernel - Re: [PATCH] clk: s2mps11: Fix double free corruption during driver unbind

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Date:	Fri, 27 Jun 2014 14:03:14 +0200
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Yadwinder Singh Brar <yadi.brar01@...il.com>
Cc:	Mike Turquette <mturquette@...aro.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Tomasz Figa <t.figa@...sung.com>,
	Yadwinder Singh Brar <yadi.brar@...sung.com>,
	Tushar Behera <tushar.behera@...aro.org>
Subject: Re: [PATCH] clk: s2mps11: Fix double free corruption during driver
 unbind

On pią, 2014-06-27 at 17:19 +0530, Yadwinder Singh Brar wrote:
> Hi Krzystof,
> 
> On Fri, Jun 27, 2014 at 4:04 PM, Krzysztof Kozlowski
> <k.kozlowski@...sung.com> wrote:
> > After unbinding the driver memory was corrupted by double free of
> > clk_lookup structure. This lead to OOPS when re-binding the driver
> > again.
> >
> > The driver allocated memory for 'clk_lookup' with devm_kzalloc. During
> > driver removal this memory was freed twice: once by clkdev_drop() and
> > second by devm code.
> >
> 
> Ideally memory should be allocated and deallocated in same place
> either driver or framework, so in this case if framework(clkdev_drop)
> deallocates memory, framework itself should also allocate it.
> So IMO this bug should be fixed using clkdev_alloc() instead of kzalloc().
> 

You're right, I'll send fixed version. Thanks for idea.

Best regards,
Krzysztof

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