linux-kernel - [147/151] intel-iommu: Fix oops with intel_iommu=igfx

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Date:	Wed, 16 Dec 2009 19:57:24 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	David Woodhouse <David.Woodhouse@...el.com>
Subject: [147/151] intel-iommu: Fix oops with intel_iommu=igfx_off

2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------

From: David Woodhouse <David.Woodhouse@...el.com>

commit 44cd613c0e4cd93079ea2a93aa06649d8ca0830a upstream.

The hotplug notifier will call find_domain() to see if the device in
question has been assigned an IOMMU domain. However, this should never
be called for devices with a "dummy" domain, such as graphics devices
when intel_iommu=igfx_off is set and the corresponding IOMMU isn't even
initialised. If you do that, it'll oops as it dereferences the (-1)
pointer.

The notifier function should check iommu_no_mapping() for the
device before doing anything else.

Signed-off-by: David Woodhouse <David.Woodhouse@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/pci/intel-iommu.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -3238,6 +3238,9 @@ static int device_notifier(struct notifi
 	struct pci_dev *pdev = to_pci_dev(dev);
 	struct dmar_domain *domain;

+	if (iommu_no_mapping(dev))
+		return 0;
+
 	domain = find_domain(pdev);
 	if (!domain)
 		return 0;

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