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From: Pavel Machek <pavel@ucw.cz>
To: Suman Anna <s-anna@ti.com>
Cc: "Robin Murphy" <robin.murphy@arm.com>,
	ivo.g.dimitrov.75@gmail.com, khilman@kernel.org,
	"Tony Lindgren" <tony@atomide.com>,
	aaro.koskinen@iki.fi,
	"kernel list" <linux-kernel@vger.kernel.org>,
	sre@kernel.org, martijn@brixit.nl,
	"Filip Matijević" <filip.matijevic.pz@gmail.com>,
	abcloriens@gmail.com, sakari.ailus@linux.intel.com,
	pali.rohar@gmail.com, clayton@craftyguy.net,
	linux-omap@vger.kernel.org, patrikbachan@gmail.com,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	serge@hallyn.com
Subject: Re: Nokia N900: refcount_t underflow, use after free
Date: Fri, 9 Mar 2018 23:18:34 +0100	[thread overview]
Message-ID: <20180309221834.GA15476@amd> (raw)
In-Reply-To: <1643b74a-62ba-bea6-71c2-a2dd02430463@ti.com>

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On Fri 2018-03-09 16:13:36, Suman Anna wrote:
> On 03/09/2018 06:08 AM, Robin Murphy wrote:
> > On 08/03/18 18:50, Pavel Machek wrote:
> >> Hi!
> >>
> >>>> * Pavel Machek <pavel@ucw.cz> [180308 14:31]:
> >>>>> Hi!
> >>>>>
> >>>>> I'm getting this warning... Has anyone seen/debugged that before?
> >>>>> Unfortunately the backtrace does not seem to be too useful :-(.
> >>>>
> >>>> Adding Suman to Cc, as it points to arm_iommu_release_mapping().
> >>>
> >>> Hmm, we need to find out if the failure paths in isp_probe() are
> >>> mismatched, or if this is coming from some mismatch between the OMAP
> >>> IOMMU driver and the DMA plumbing. AFAIK, the cleanup paths in this
> >>
> >> Well, camera only started to work on N900 pretty recently. Let me add
> >> some debug printks...
> >>
> >> Camera does not work in 4.16.0-rc4-next-20180308-dirty.
> >>
> >> I see this. It looks like problem in isp error paths, indeed:
> > 
> > Well, there certainly seems to be an obvious bug wherein
> > isp_detach_iommu() just releases the mapping directly without calling
> > arm_iommu_detach_device() to balance the equivalent attach. That can't
> > be helping.
> 
> Indeed, I have been able to reproduce the same warning using a
> standalone test module, and the missing arm_iommu_detach_device() is
> causing the warning after probe (during failure path) or during
> remove.

Ok do you have an idea how to fix the isp error paths? Untested patch
would be fine... But it seems that you know what needs to be fixed and
I don't.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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WARNING: multiple messages have this Message-ID (diff)
From: pavel@ucw.cz (Pavel Machek)
To: linux-arm-kernel@lists.infradead.org
Subject: Nokia N900: refcount_t underflow, use after free
Date: Fri, 9 Mar 2018 23:18:34 +0100	[thread overview]
Message-ID: <20180309221834.GA15476@amd> (raw)
In-Reply-To: <1643b74a-62ba-bea6-71c2-a2dd02430463@ti.com>

On Fri 2018-03-09 16:13:36, Suman Anna wrote:
> On 03/09/2018 06:08 AM, Robin Murphy wrote:
> > On 08/03/18 18:50, Pavel Machek wrote:
> >> Hi!
> >>
> >>>> * Pavel Machek <pavel@ucw.cz> [180308 14:31]:
> >>>>> Hi!
> >>>>>
> >>>>> I'm getting this warning... Has anyone seen/debugged that before?
> >>>>> Unfortunately the backtrace does not seem to be too useful :-(.
> >>>>
> >>>> Adding Suman to Cc, as it points to arm_iommu_release_mapping().
> >>>
> >>> Hmm, we need to find out if the failure paths in isp_probe() are
> >>> mismatched, or if this is coming from some mismatch between the OMAP
> >>> IOMMU driver and the DMA plumbing. AFAIK, the cleanup paths in this
> >>
> >> Well, camera only started to work on N900 pretty recently. Let me add
> >> some debug printks...
> >>
> >> Camera does not work in 4.16.0-rc4-next-20180308-dirty.
> >>
> >> I see this. It looks like problem in isp error paths, indeed:
> > 
> > Well, there certainly seems to be an obvious bug wherein
> > isp_detach_iommu() just releases the mapping directly without calling
> > arm_iommu_detach_device() to balance the equivalent attach. That can't
> > be helping.
> 
> Indeed, I have been able to reproduce the same warning using a
> standalone test module, and the missing arm_iommu_detach_device() is
> causing the warning after probe (during failure path) or during
> remove.

Ok do you have an idea how to fix the isp error paths? Untested patch
would be fine... But it seems that you know what needs to be fixed and
I don't.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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  reply	other threads:[~2018-03-09 22:18 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-08 14:30 Nokia N900: refcount_t underflow, use after free Pavel Machek
2018-03-08 14:30 ` Pavel Machek
2018-03-08 16:59 ` Tony Lindgren
2018-03-08 16:59   ` Tony Lindgren
2018-03-08 18:21   ` Suman Anna
2018-03-08 18:21     ` Suman Anna
2018-03-08 18:50     ` Pavel Machek
2018-03-08 18:50       ` Pavel Machek
2018-03-09 12:08       ` Robin Murphy
2018-03-09 12:08         ` Robin Murphy
2018-03-09 22:13         ` Suman Anna
2018-03-09 22:13           ` Suman Anna
2018-03-09 22:13           ` Suman Anna
2018-03-09 22:18           ` Pavel Machek [this message]
2018-03-09 22:18             ` Pavel Machek
2018-03-09 23:06             ` Suman Anna
2018-03-09 23:06               ` Suman Anna
2018-03-10 11:26               ` Pavel Machek
2018-03-10 11:26                 ` Pavel Machek
2018-03-12 16:10                 ` Suman Anna
2018-03-12 16:10                   ` Suman Anna
2018-03-12 16:10                   ` Suman Anna
2018-05-24 11:05                   ` Pavel Machek
2018-05-24 11:05                     ` Pavel Machek
2018-05-25  2:37                     ` Suman Anna
2018-05-25  2:37                       ` Suman Anna

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