In the Linux kernel, the following vulnerability has been resolved:
ACPI: processor: Fix NULL-pointer dereference in acpi_processor_errata_piix4()
In acpi_processor_errata_piix4(), the pointer dev is first assigned an IDE
device and then reassigned an ISA device:
dev = pci_get_subsys(..., PCI_DEVICE_ID_INTEL_82371AB, ...);
dev = pci_get_subsys(..., PCI_DEVICE_ID_INTEL_82371AB_0, ...);
If the first lookup succeeds but the second fails, dev becomes NULL. This
leads to a potential null-pointer dereference when dev_dbg() is called:
if (errata.piix4.bmisx)
dev_dbg(&dev->dev, ...);
To prevent this, use two temporary pointers and retrieve each device
independently, avoiding overwriting dev with a possible NULL value.
[ rjw: Subject adjustment, added an empty code line ]