linux-kernel - Re: [PATCH] ACPI / PNP: Do not crash due to stale pointer use during system resume

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Message-ID: <28227702.6DTxM78Dej@vostro.rjw.lan>
Date:	Fri, 30 Nov 2012 00:51:25 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Shuah Khan <shuahkhan@...il.com>
Cc:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Zdenek Kabelac <zdenek.kabelac@...il.com>
Subject: Re: [PATCH] ACPI / PNP: Do not crash due to stale pointer use during system resume

On Thursday, November 29, 2012 04:25:20 PM Shuah Khan wrote:
> On Thu, Nov 29, 2012 at 4:10 PM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >
> > During resume from system suspend the 'data' field of
> > struct pnp_dev in pnpacpi_set_resources() may be a stale pointer,
> > due to removal of the associated ACPI device node object in the
> > previous suspend-resume cycle.  This happens, for example, if a
> > dockable machine is booted in the docking station and then suspended
> > and resumed and suspended again.  If that happens,
> > pnpacpi_build_resource_template() called from pnpacpi_set_resources()
> > attempts to use that pointer and crashes.
> >
> > However, pnpacpi_set_resources() actually checks the device's ACPI
> > handle, attempts to find the ACPI device node object attached to it
> > and returns an error code if that fails, so in fact it knows what the
> > correct value of dev->data should be.  Use this observation to update
> > dev->data with the correct value if necessary and dump a call trace
> > if that's the case (once).
> >
> > We still need to fix the root cause of this issue, but preventing
> > systems from crashing because of it is an improvement too.
> >
> > Reported-and-tested-by: Zdenek Kabelac <zdenek.kabelac@...il.com>
> > References: https://bugzilla.kernel.org/show_bug.cgi?id=51071
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> Any reason why this shouldn't go into stable releases?

Yes, it can go to -stable.  This is just a patch, not a git commit.  I can
still add the "stable" tag to it when it goes to git. :-)

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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