linux-kernel - Re: [PATCH] xhci: fix null-pointer dereference when destroying half-built segment rings

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Message-ID: <20121112180337.GB6217@xanatos>
Date:	Mon, 12 Nov 2012 10:03:37 -0800
From:	Sarah Sharp <sarah.a.sharp@...ux.intel.com>
To:	Julius Werner <jwerner@...gle.com>
Cc:	Andy Shevchenko <andy.shevchenko@...il.com>,
	Julius Werner <jwerner@...omium.org>,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Vincent Palatin <vpalatin@...omium.org>
Subject: Re: [PATCH] xhci: fix null-pointer dereference when destroying
 half-built segment rings

On Thu, Nov 01, 2012 at 01:28:46PM -0700, Julius Werner wrote:
> >> Is it just
> >> for (prev = *first; prev; prev = prev->next)
> >>    xhci_segment_free(xhci, prev);
> >> 
> >> ?
> > 
> > Yeah, that seems cleaner.
> > 
> > Sarah Sharp
> 
> I can submit it that way if you want, but I would advise against it. This way you access the prev pointer after it has been freed already… that's probably not a problem in the current kernel, but it depends on how the underlying memory is managed and is generally just not a good idea in my opinion.

Yep, you're right.  I'll take the second patch you submitted, thanks.

Sarah Sharp
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