Commit 412af978 authored by Troy Moure's avatar Troy Moure Committed by Len Brown

ACPI: video: prevent NULL deref in acpi_get_pci_dev()

ref: http://thread.gmane.org/gmane.linux.kernel/857228/focus=857468

When the ACPI video driver initializes, it does a namespace walk
looking for for supported devices. When we find an appropriate
handle, we walk up the ACPI tree looking for a PCI root bus, and
then walk back down the PCI bus, assuming that every device
inbetween is a P2P bridge.

This assumption is not correct, and is reported broken on at
least:

	Dell Latitude E6400
	ThinkPad X61
	Dell XPS M1330

Add a NULL deref check to prevent boot panics.
Reported-by: default avatarAlessandro Suardi <alessandro.suardi@gmail.com>
Signed-off-by: default avatarTroy Moure <twmoure@szypr.net>
Signed-off-by: default avatarAlex Chiang <achiang@hp.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent 3cd530b5
......@@ -395,7 +395,7 @@ struct pci_dev *acpi_get_pci_dev(acpi_handle handle)
fn = adr & 0xffff;
pdev = pci_get_slot(pbus, PCI_DEVFN(dev, fn));
if (hnd == handle)
if (!pdev || hnd == handle)
break;
pbus = pdev->subordinate;
......
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