In the Linux kernel, the following vulnerability has been resolved: ACPI: processor: Fix NULL-pointer dereference in acpiprocessorerratapiix4() In acpiprocessorerratapiix4(), the pointer dev is first assigned an IDE device and then reassigned an ISA device: dev = pcigetsubsys(..., PCIDEVICEIDINTEL82371AB, ...); dev = pcigetsubsys(..., PCIDEVICEIDINTEL82371AB0, ...); If the first lookup succeeds but the second fails, dev becomes NULL. This leads to a potential null-pointer dereference when devdbg() 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 ]