Linux Kernel: Null Pointer Deref in EFI Runtime Workqueue Before ACPI Init
CVE-2026-64183 Published on July 19, 2026
efi: Allocate runtime workqueue before ACPI init
In the Linux kernel, the following vulnerability has been resolved:
efi: Allocate runtime workqueue before ACPI init
Since commit
5894cf571e14 ("acpi/prmt: Use EFI runtime sandbox to invoke PRM handlers")
ACPI PRM calls are delegated to a workqueue which runs in a kernel
thread, making it easier to detect and mitigate faulting memory accesses
performed by the firmware.
Rafael reports that such PRM accesses may occur before efisubsys_init()
executes, which is where the workqueue is allocated, leading to NULL
pointer dereferences. Since acpi_init() [which triggers the early PRM
accesses] executes as a subsys_initcall() as well, and has its own
dependencies that may be sensitive to initcall ordering, deferring
acpi_init() is not an option.
So instead, split off the workqueue allocation into its own postcore
initcall, as this is the only missing piece to allow EFI runtime calls
to be made. This ensures that EFI runtime call (including PRM calls) are
accessible to all code running at subsys_initcall() level.
Products Associated with CVE-2026-64183
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Affected Versions
Linux:- Version 5894cf571e14fb393a4d0a82538de032127b9d8b and below 29cd94e678fcb3c4fd0f359deeac6d61334323fc is affected.
- Version 5894cf571e14fb393a4d0a82538de032127b9d8b and below 6996e954ae830f5b793ba6cf449885ca519dbdd2 is affected.
- Version 5894cf571e14fb393a4d0a82538de032127b9d8b and below c32a1fbe0f9a48453a552bb315cc4f1e7a74084e is affected.
- Version 5894cf571e14fb393a4d0a82538de032127b9d8b and below e871549f7894ad4114b3dd53f241aa25a268ba8b is affected.
- Version 5894cf571e14fb393a4d0a82538de032127b9d8b and below 13c6da02e767152c9ac4330962247a5e47011035 is affected.
- Version 6.6 is affected.
- Before 6.6 is unaffected.
- Version 6.6.142, <= 6.6.* is unaffected.
- Version 6.12.92, <= 6.12.* is unaffected.
- Version 6.18.34, <= 6.18.* is unaffected.
- Version 7.0.11, <= 7.0.* is unaffected.
- Version 7.1, <= * is unaffected.