Bug 2482014 (CVE-2026-45968)

Summary: CVE-2026-45968 kernel: cpuidle: Skip governor when only one idle state is available
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's cpuidle subsystem. On certain PowerNV systems, when only a single idle state is available, the cpuidle ladder governor may incorrectly treat state 1 as usable. This can lead to an out-of-bounds index being passed, causing a NULL enter callback to be invoked and ultimately resulting in a system crash, leading to a denial of service.
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Description OSIDB Bzimport 2026-05-27 15:07:08 UTC 
In the Linux kernel, the following vulnerability has been resolved:

cpuidle: Skip governor when only one idle state is available

On certain platforms (PowerNV systems without a power-mgt DT node),
cpuidle may register only a single idle state. In cases where that
single state is a polling state (state 0), the ladder governor may
incorrectly treat state 1 as the first usable state and pass an
out-of-bounds index. This can lead to a NULL enter callback being
invoked, ultimately resulting in a system crash.

[   13.342636] cpuidle-powernv : Only Snooze is available
[   13.351854] Faulting instruction address: 0x00000000
[   13.376489] NIP [0000000000000000] 0x0
[   13.378351] LR  [c000000001e01974] cpuidle_enter_state+0x2c4/0x668

Fix this by adding a bail-out in cpuidle_select() that returns state 0
directly when state_count <= 1, bypassing the governor and keeping the
tick running.
Comment 1 Keith Grant 2026-05-27 22:58:01 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026052735-CVE-2026-45968-489e@gregkh/T