CVE-2024-26646: thermal: intel: hfi: Add syscore callbacks for system-wide PM
In the Linux kernel, the following vulnerability has been resolved:
thermal: intel: hfi: Add syscore callbacks for system-wide PM
The kernel allocates a memory buffer and provides its location to the
hardware, which uses it to update the HFI table. This allocation occurs
during boot and remains constant throughout runtime.
When resuming from hibernation, the restore kernel allocates a second
memory buffer and reprograms the HFI hardware with the new location as
part of a normal boot. The location of the second memory buffer may
differ from the one allocated by the image kernel.
When the restore kernel transfers control to the image kernel, its HFI
buffer becomes invalid, potentially leading to memory corruption if the
hardware writes to it (the hardware continues to use the buffer from the
restore kernel).
It is also possible that the hardware "forgets" the address of the memory
buffer when resuming from "deep" suspend. Memory corruption may also occur
in such a scenario.
To prevent the described memory corruption, disable HFI when preparing to
suspend or hibernate. Enable it when resuming.
Add syscore callbacks to handle the package of the boot CPU (packages of
non-boot CPUs are handled via CPU offline). Syscore ops always run on the
boot CPU. Additionally, HFI only needs to be disabled during "deep" suspend
and hibernation. Syscore ops only run in these cases.
[ rjw: Comment adjustment, subject and changelog edits ]
Security readout for executives and security teams
Plain-English summary
A Linux kernel flaw can corrupt memory when an affected Intel Hardware Feedback Interface system returns from hibernation or deep suspend. The hardware may retain or lose an invalid buffer address and write to unintended memory. This can threaten system confidentiality, integrity, and availability, but requires local access and a qualifying power-management transition.
Executive priority
Prioritize affected Intel Linux endpoints and servers that use hibernation or deep suspend, especially multi-user systems where untrusted local accounts exist. Internet-facing status alone does not drive this risk because the stated attack vector is local. Patch through normal vendor channels promptly, with accelerated handling for systems repeatedly entering affected power states.
Technical view
During resume, the restore kernel can give Intel HFI a newly allocated table buffer. Control then returns to the image kernel while hardware may continue using the restore kernel’s now-invalid buffer. Deep suspend can produce a related address-loss condition. The kernel fix adds syscore callbacks that disable HFI before deep suspend or hibernation and re-enable it during resume.
Likely exposure
Exposure is limited to Linux systems using the affected Intel HFI kernel functionality and deep suspend or hibernation. The supplied record identifies affected kernel releases including 5.18, 6.1.76, 6.6.15, 6.7.3, and 6.8, but does not provide clear distribution-specific package boundaries. Vendor backports may change actual exposure.
Exploitation context
The CVSS 3.1 score is 7.8 with a local, low-privilege vector and no user interaction. The supplied record is not in KEV and provides no evidence of active exploitation or a public exploit. Practical exploitability is not established by these sources.
Researcher notes
The failure is a stale or forgotten hardware buffer address across system-wide power transitions, creating hardware-initiated writes into invalid memory. The record supplies four stable-kernel commits but no CWE, public proof of concept, observed exploitation, or reliable distribution package mapping. Review the relevant branch-specific commit and downstream backport before declaring a system fixed.
Mitigation direction
Install a vendor-supported kernel containing the applicable stable fix.
Check distribution advisories for backported fixes and precise package versions.
Until patched, consider avoiding hibernation and deep suspend on potentially affected HFI systems.
Follow vendor guidance before changing or disabling production power-management behavior.
Validation and detection
Inventory Linux kernel and distribution package versions on Intel systems.
Determine whether Intel HFI functionality is present and active.
Identify systems permitted to enter hibernation or deep suspend.
Confirm the installed kernel includes the applicable stable fix or vendor backport.
After updating, test suspend and resume stability under controlled conditions.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Potential ATT&CK relevance
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