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From: David Brownell <david-b@pacbell.net>
To: lrg@slimlogic.co.uk, broonie@opensource.wolfsonmicro.com
Subject: Re: [PATCH] regulator core: fix double-free in regulator_register() error path
Date: Sat, 25 Apr 2009 15:11:56 -0700
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Cc: Paul Walmsley <paul@pwsan.com>, linux-kernel@vger.kernel.org,
       linux-omap@vger.kernel.org
References: <alpine.DEB.2.00.0904250526210.28378@utopia.booyaka.com>
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On Saturday 25 April 2009, Paul Walmsley wrote:
> 
> During regulator registration, any error after device_register() will 
> cause a double-free on the struct regulator_dev 'rdev'.  The bug is in 
> drivers/regulator/core.c:regulator_register():
> 
> ...
> scrub:
> 	device_unregister(&rdev->dev);
> clean:
> 	kfree(rdev);                           <---
> 	rdev = ERR_PTR(ret);
> 	goto out;
> ...
> 
> device_unregister() calls regulator_dev_release() which frees rdev.  The 
> subsequent kfree corrupts memory and causes some OMAP3 systems to oops on 
> boot in regulator_get().
> 
> Applies against 2.6.30-rc3.
> 
> Signed-off-by: Paul Walmsley <paul@pwsan.com>

This looks like it would address the oopsing I mentioned a
while back, since affects cleanup paths after errors during
driver probe().


> ---
>  drivers/regulator/core.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
> index 01f7702..fabd2e0 100644
> --- a/drivers/regulator/core.c
> +++ b/drivers/regulator/core.c
> @@ -2080,6 +2080,10 @@ out:
>  
>  scrub:
>  	device_unregister(&rdev->dev);
> +	/* device core frees rdev */
> +	rdev = ERR_PTR(ret);
> +	goto out;
> +
>  clean:
>  	kfree(rdev);
>  	rdev = ERR_PTR(ret);
> -- 
> 1.6.3.rc1.51.gea0b7
> 
> 


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