CVE-2026-45968cpuidle: Skip governor when only one idle state is available

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/a0f7e804edc82e513d1ccb7c95ed8b351522ec81
• https://git.kernel.org/stable/c/5d103a38e2ae96eca57fd17161bcd29bd4622d1c
• https://git.kernel.org/stable/c/4da2b897283c39980d6ae09dc1560fcd937879e5
• https://git.kernel.org/stable/c/5c577ac939bca486cb02069505cfe47a5312ce02
• https://git.kernel.org/stable/c/8f6833d919bae915ead6c599a53e81e19b32da52
• https://git.kernel.org/stable/c/63ae78336f40bcd9a44952a7c6bafb9c88a8effd
• https://git.kernel.org/stable/c/a0724e40a58a0e323c59707edeae5b71d15800dc
• https://git.kernel.org/stable/c/e5c9ffc6ae1bcdb1062527d611043681ac301aca