In the Linux kernel, the following vulnerability has been resolved: ACPI: fix NULL pointer dereference Commit 71f642833284 ("ACPI: utils: Fix reference counting in foreachacpidevmatch()") started doing "acpidevput()" on a pointer that was possibly NULL. That fails miserably, because that helper inline function is not set up to handle that case. Just make acpidevput() silently accept a NULL pointer, rather than calling down to put_device() with an invalid offset off that NULL pointer.