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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: [PATCH v2] iommu/vt-d: race setting IRQ CPU affinity while freeing IRQ
Date: Wed, 23 Jul 2014 10:13:26 -0600	[thread overview]
Message-ID: <20140723161326.GB32422@psuche.datadirectnet.com> (raw)
In-Reply-To: <20140723151040.GB14017@8bytes.org>

A user process setting the CPU affinity of an IRQ for a KVM
direct-assigned device via /proc/irq/<IRQ#>/smp_affinity can race with
the IRQ being released by QEMU, resulting in a NULL iommu pointer
dereference in get_irte().

Signed-off-by: Greg Edwards <gedwards@ddn.com>
---

Dropped the Cc: for stable since this likely wouldn't ever be seen in
the real world.  We saw it on an automated CI stress test.

 drivers/iommu/intel_irq_remapping.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index 9b17489..d926676 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -70,6 +70,11 @@ static int get_irte(int irq, struct irte *entry)
 
 	raw_spin_lock_irqsave(&irq_2_ir_lock, flags);
 
+	if (unlikely(!irq_iommu->iommu)) {
+		raw_spin_unlock_irqrestore(&irq_2_ir_lock, flags);
+		return -1;
+	}
+
 	index = irq_iommu->irte_index + irq_iommu->sub_handle;
 	*entry = *(irq_iommu->iommu->ir_table->base + index);
 
-- 
1.9.3


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: [PATCH v2] iommu/vt-d: race setting IRQ CPU affinity while freeing IRQ
Date: Wed, 23 Jul 2014 10:13:26 -0600	[thread overview]
Message-ID: <20140723161326.GB32422@psuche.datadirectnet.com> (raw)
In-Reply-To: <20140723151040.GB14017-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>

A user process setting the CPU affinity of an IRQ for a KVM
direct-assigned device via /proc/irq/<IRQ#>/smp_affinity can race with
the IRQ being released by QEMU, resulting in a NULL iommu pointer
dereference in get_irte().

Signed-off-by: Greg Edwards <gedwards-LfVdkaOWEx8@public.gmane.org>
---

Dropped the Cc: for stable since this likely wouldn't ever be seen in
the real world.  We saw it on an automated CI stress test.

 drivers/iommu/intel_irq_remapping.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index 9b17489..d926676 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -70,6 +70,11 @@ static int get_irte(int irq, struct irte *entry)
 
 	raw_spin_lock_irqsave(&irq_2_ir_lock, flags);
 
+	if (unlikely(!irq_iommu->iommu)) {
+		raw_spin_unlock_irqrestore(&irq_2_ir_lock, flags);
+		return -1;
+	}
+
 	index = irq_iommu->irte_index + irq_iommu->sub_handle;
 	*entry = *(irq_iommu->iommu->ir_table->base + index);
 
-- 
1.9.3

  reply	other threads:[~2014-07-23 16:13 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
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       ` Greg Edwards [this message]
2014-07-23 16:13         ` [PATCH v2] iommu/vt-d: race setting IRQ CPU affinity while freeing IRQ 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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