ACPI: video: prevent NULL deref in acpi_get_pci_dev()
authorTroy Moure <twmoure@szypr.net>
Thu, 25 Jun 2009 23:05:35 +0000 (17:05 -0600)
committerLen Brown <len.brown@intel.com>
Fri, 26 Jun 2009 04:23:42 +0000 (00:23 -0400)
commit412af97838828bc6d035a1902c8974f944663da6
treef50b1de9aa3ab2c4ae7db0bf4afeb7f1cc6b2163
parent3cd530b5aaffd27b231f9717730f2f6684c00bda
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: Alessandro Suardi <alessandro.suardi@gmail.com>
Signed-off-by: Troy Moure <twmoure@szypr.net>
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>
drivers/acpi/pci_root.c