From: Greg Edwards <gedwards@ddn.com>
To: Joerg Roedel <joro@8bytes.org>
Cc: David Woodhouse <dwmw2@infradead.org>,
<iommu@lists.linux-foundation.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] iommu/vt-d: fix race between free_irte() and get_irte()
Date: Wed, 23 Jul 2014 08:49:17 -0600 [thread overview]
Message-ID: <20140723144917.GA26986@psuche.datadirectnet.com> (raw)
In-Reply-To: <20140723144024.GA14017@8bytes.org>
On Wed, Jul 23, 2014 at 04:40:24PM +0200, Joerg Roedel wrote:
> On Tue, Jul 22, 2014 at 08:27:19AM -0600, Greg Edwards wrote:
>> get_irte() can race with free_irte() and dereference a NULL iommu
>> pointer.
>
> Have you seen any real occurance of this race? Get_irte is called in the
> set_affinity path, how can that race with the irq being freed?
Yes, that's how we hit it. A process was setting the CPU affinity while
QEMU was releasing the IRQ. We have a CI stress test that turned this
up.
Greg
WARNING: multiple messages have this Message-ID (diff)
From: Greg Edwards <gedwards-LfVdkaOWEx8@public.gmane.org>
To: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
David Woodhouse <dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] iommu/vt-d: fix race between free_irte() and get_irte()
Date: Wed, 23 Jul 2014 08:49:17 -0600 [thread overview]
Message-ID: <20140723144917.GA26986@psuche.datadirectnet.com> (raw)
In-Reply-To: <20140723144024.GA14017-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
On Wed, Jul 23, 2014 at 04:40:24PM +0200, Joerg Roedel wrote:
> On Tue, Jul 22, 2014 at 08:27:19AM -0600, Greg Edwards wrote:
>> get_irte() can race with free_irte() and dereference a NULL iommu
>> pointer.
>
> Have you seen any real occurance of this race? Get_irte is called in the
> set_affinity path, how can that race with the irq being freed?
Yes, that's how we hit it. A process was setting the CPU affinity while
QEMU was releasing the IRQ. We have a CI stress test that turned this
up.
Greg
next prev parent reply other threads:[~2014-07-23 14:49 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-22 14:27 [PATCH] iommu/vt-d: fix race between free_irte() and get_irte() Greg Edwards
2014-07-22 14:27 ` Greg Edwards
2014-07-23 14:40 ` Joerg Roedel
2014-07-23 14:40 ` Joerg Roedel
2014-07-23 14:49 ` Greg Edwards [this message]
2014-07-23 14:49 ` Greg Edwards
2014-07-23 15:10 ` Joerg Roedel
2014-07-23 15:10 ` Joerg Roedel
2014-07-23 16:13 ` [PATCH v2] iommu/vt-d: race setting IRQ CPU affinity while freeing IRQ Greg Edwards
2014-07-23 16:13 ` Greg Edwards
2014-07-29 10:45 ` Joerg Roedel
2014-07-29 10:45 ` Joerg Roedel
2014-07-29 17:21 ` Greg Edwards
2014-07-29 17:21 ` Greg Edwards
2014-07-31 11:49 ` Joerg Roedel
2014-07-31 11:49 ` Joerg Roedel
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