Description
In the Linux kernel, the following vulnerability has been resolved:
hrtimers: Handle CPU state correctly on hotplug
Consider a scenario where a CPU transitions from CPUHP_ONLINE to halfway
through a CPU hotunplug down to CPUHP_HRTIMERS_PREPARE, and then back to
CPUHP_ONLINE:
Since hrtimers_prepare_cpu() does not run, cpu_base.hres_active remains set
to 1 throughout. However, during a CPU unplug operation, the tick and the
clockevents are shut down at CPUHP_AP_TICK_DYING. On return to the online
state, for instance CFS incorrectly assumes that the hrtick is already
active, and the chance of the clockevent device to transition to oneshot
mode is also lost forever for the CPU, unless it goes back to a lower state
than CPUHP_HRTIMERS_PREPARE once.
This round-trip reveals another issue; cpu_base.online is not set to 1
after the transition, which appears as a WARN_ON_ONCE in enqueue_hrtimer().
Aside of that, the bulk of the per CPU state is not reset either, which
means there are dangling pointers in the worst case.
Address this by adding a corresponding startup() callback, which resets the
stale per CPU state and sets the online flag.
[ tglx: Make the new callback unconditionally available, remove the online
modification in the prepare() callback and clear the remaining
state in the starting callback instead of the prepare callback ]
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Linux | Linux | 5.4.264 – < 5.4.290, 5.10.204 – < 5.10.234, 5.15.143 – < 5.15.177, 6.1.68 – < 6.1.127, 6.6.7 – < 6.6.74, 4.19.302 – < 4.20, 6.7 | 5.4.290 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | linux | 6.12.11-1 | — |
| Debian 13 | linux | 6.12.11-1 | — |
| Debian 12 | linux | 6.1.128-1 | — |
| Debian 11 | linux | 5.10.234-1 | DLA-4075-1 |
| Debian 11 | linux-6.1 | 6.1.128-1~deb11u1 | DLA-4076-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Nvidia-BlueField 22.04 LTS | linux-bluefield | 5.15.0-1062.64 | — |
| Ubuntu 24.04 LTS | linux | 6.8.0-62.65 | USN-7595-1 |
| Ubuntu 24.04 LTS | linux-aws | 6.8.0-1030.32 | USN-7595-1 |
| Ubuntu 24.04 LTS | linux-azure | 6.8.0-1030.35 | USN-7596-1 |
| Ubuntu 24.04 LTS | linux-azure-nvidia | 6.8.0-1018.19 | USN-7596-2 |
| Ubuntu 24.04 LTS | linux-gcp | 6.8.0-1031.33 | USN-7595-5 |
| Ubuntu 24.04 LTS | linux-gcp-6.11 +1 | 6.11.0-1013.13~24.04.1 | USN-7448-1 |
| Ubuntu 24.04 LTS | linux-gke | 6.8.0-1026.30 | USN-7595-1 |
| Ubuntu 24.04 LTS | linux-gkeop | 6.8.0-1013.15 | USN-7595-1 |
| Ubuntu 24.04 LTS | linux-hwe-6.11 | 6.11.0-24.24~24.04.1 | USN-7445-1 |
| Ubuntu 24.04 LTS | linux-ibm | 6.8.0-1027.27 | USN-7595-1 |
| Ubuntu 24.04 LTS | linux-lowlatency | 6.8.0-62.65.1 | USN-7595-1 |
| Ubuntu 24.04 LTS | linux-lowlatency-hwe-6.11 | 6.11.0-1012.13~24.04.1 | USN-7445-1 |
| Ubuntu 24.04 LTS | linux-nvidia | 6.8.0-1029.32 | USN-7595-1 |
| Ubuntu 24.04 LTS | linux-nvidia-6.11 | 6.11.0-1007.7 | — |
| Ubuntu 24.04 LTS | linux-nvidia-lowlatency | 6.8.0-1029.32.1 | USN-7595-1 |
| Ubuntu 24.04 LTS | linux-nvidia-tegra | 6.8.0-1008.8 | — |
| Ubuntu 24.04 LTS | linux-oem-6.11 | 6.11.0-1020.20 | USN-7445-1 |
| Ubuntu 24.04 LTS | linux-oem-6.8 | 6.8.0-1029.29 | USN-7595-1 |
| Ubuntu 24.04 LTS | linux-oracle | 6.8.0-1027.28 | USN-7595-4 |
| Ubuntu 24.04 LTS | linux-raspi | 6.8.0-1029.33 | USN-7595-4 |
| Ubuntu 24.04 LTS | linux-riscv +2 | No fix yet | — |
| Ubuntu 24.04 LTS | linux-xilinx | 6.8.0-1017.18 | — |
| Ubuntu 22.04 LTS | linux +1 | 5.15.0-135.146 | USN-7387-1 |
| Ubuntu 22.04 LTS | linux-aws | 5.15.0-1080.87 | USN-7387-1 |
| Ubuntu 22.04 LTS | linux-aws-6.8 | 6.8.0-1030.32~22.04.1 | USN-7595-1 |
| Ubuntu 22.04 LTS | linux-azure | 5.15.0-1084.93 | USN-7387-1 |
| Ubuntu 22.04 LTS | linux-azure-6.8 | 6.8.0-1030.35~22.04.1 | USN-7596-1 |
| Ubuntu 22.04 LTS | linux-azure-fde | 5.15.0-1084.93.1 | — |
| Ubuntu 22.04 LTS | linux-gcp | 5.15.0-1079.88 | USN-7387-1 |
| Ubuntu 22.04 LTS | linux-gcp-6.8 | 6.8.0-1031.33~22.04.1 | USN-7595-5 |
| Ubuntu 22.04 LTS | linux-gke +1 | 5.15.0-1077.83 | USN-7387-1 |
| Ubuntu 22.04 LTS | linux-gkeop | 5.15.0-1062.70 | USN-7387-1 |
| Ubuntu 22.04 LTS | linux-hwe-6.8 | 6.8.0-64.67~22.04.1 | USN-7653-1 |
| Ubuntu 22.04 LTS | linux-ibm | 5.15.0-1072.75 | USN-7387-1 |
| Ubuntu 22.04 LTS | linux-ibm-6.8 | 6.8.0-1027.27~22.04.1 | — |
| Ubuntu 22.04 LTS | linux-intel-iot-realtime | 5.15.0-1073.75 | — |
| Ubuntu 22.04 LTS | linux-intel-iotg | 5.15.0-1075.81 | USN-7387-1 |
| Ubuntu 22.04 LTS | linux-kvm | 5.15.0-1076.81 | USN-7388-1 |
| Ubuntu 22.04 LTS | linux-lowlatency-hwe-6.8 | 6.8.0-62.65.1~22.04.1 | USN-7595-1 |
| Ubuntu 22.04 LTS | linux-nvidia | 5.15.0-1074.75 | USN-7387-1 |
| Ubuntu 22.04 LTS | linux-nvidia-6.8 | 6.8.0-1029.32~22.04.1 | USN-7595-1 |
| Ubuntu 22.04 LTS | linux-nvidia-tegra | 5.15.0-1033.33 | USN-7389-1 |
| Ubuntu 22.04 LTS | linux-nvidia-tegra-igx | 5.15.0-1021.21 | USN-7389-1 |
| Ubuntu 22.04 LTS | linux-oracle-6.8 | 6.8.0-1027.28~22.04.1 | USN-7595-4 |
| Ubuntu 22.04 LTS | linux-raspi | 5.15.0-1074.77 | USN-7387-1 |
| Ubuntu 22.04 LTS | linux-riscv +31 | No fix yet | — |
| Ubuntu 22.04 LTS | linux-riscv-6.8 | 6.8.0-62.65~22.04.1 | — |
| Ubuntu 22.04 LTS | linux-xilinx-zynqmp | 5.15.0-1044.48 | USN-7390-1 |
| Ubuntu 20.04 LTS | linux | 5.4.0-211.231 | USN-7391-1 |
| Ubuntu 20.04 LTS | linux-aws | 5.4.0-1142.152 | USN-7392-3 |
| Ubuntu 20.04 LTS | linux-aws-5.15 | 5.15.0-1080.87~20.04.1 | USN-7388-1 |
| Ubuntu 20.04 LTS | linux-azure | 5.4.0-1147.154 | USN-7392-1 |
| Ubuntu 20.04 LTS | linux-azure-5.15 | 5.15.0-1086.95~20.04.1 | USN-7421-1 |
| Ubuntu 20.04 LTS | linux-azure-fde-5.15 | 5.15.0-1086.95~20.04.1.1 | USN-7421-1 |
| Ubuntu 20.04 LTS | linux-bluefield | 5.4.0-1101.108 | USN-7392-1 |
| Ubuntu 20.04 LTS | linux-gcp | 5.4.0-1145.154 | USN-7392-1 |
| Ubuntu 20.04 LTS | linux-gcp-5.15 | 5.15.0-1081.90~20.04.1 | USN-7459-2 |
| Ubuntu 20.04 LTS | linux-gke +28 | No fix yet | — |
| Ubuntu 20.04 LTS | linux-hwe-5.15 | 5.15.0-136.147~20.04.1 | USN-7407-1 |
| Ubuntu 20.04 LTS | linux-ibm | 5.4.0-1088.93 | USN-7392-1 |
| Ubuntu 20.04 LTS | linux-ibm-5.15 | 5.15.0-1074.77~20.04.1 | USN-7458-1 |
| Ubuntu 20.04 LTS | linux-iot | 5.4.0-1048.51 | USN-7413-1 |
| Ubuntu 20.04 LTS | linux-kvm | 5.4.0-1129.138 | USN-7392-1 |
| Ubuntu 20.04 LTS | linux-lowlatency-hwe-5.15 | 5.15.0-135.146~20.04.1 | USN-7387-1 |
| Ubuntu 20.04 LTS | linux-oracle | 5.4.0-1140.150 | USN-7392-1 |
| Ubuntu 20.04 LTS | linux-oracle-5.15 +1 | 5.15.0-1077.83~20.04.1 | USN-7459-1, USN-7387-1 |
| Ubuntu 20.04 LTS | linux-raspi | 5.4.0-1129.142 | USN-7539-1 |
| Ubuntu 20.04 LTS | linux-riscv-5.15 | 5.15.0-1075.79~20.04.1 | — |
| Ubuntu 20.04 LTS | linux-xilinx-zynqmp | 5.4.0-1060.64 | USN-7392-1 |
| Ubuntu 18.04 LTS | linux-gcp +14 | No fix yet | — |
Show 8 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | linux-hwe-edge | No fix yet | — |
| Ubuntu Pro Realtime 24.04 LTS | linux-raspi-realtime | 6.8.0-2024.25 | USN-7595-3 |
| Ubuntu Pro Realtime 24.04 LTS | linux-realtime | 6.8.1-1023.24 | USN-7595-2 |
| Ubuntu Pro Realtime 22.04 LTS | linux-intel-iot-realtime | 5.15.0-1073.75 | USN-7387-3 |
| Ubuntu Pro Realtime 22.04 LTS | linux-realtime | 5.15.0-1080.88 | USN-7387-3 |
| Ubuntu Pro Realtime 22.04 LTS | linux-realtime-6.8 | 6.8.1-1023.24~22.04.1 | — |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-fips | 6.8.0-78.78+fips1 | — |
| Ubuntu Pro FIPS-updates 22.04 LTS | linux-aws-fips | 5.15.0-1080.87+fips1 | USN-7387-2 |
| Ubuntu Pro FIPS-updates 22.04 LTS | linux-azure-fips | 5.15.0-1083.92+fips1 | USN-7387-2 |
| Ubuntu Pro FIPS-updates 22.04 LTS | linux-fips | 5.15.0-135.146+fips1 | USN-7387-2 |
| Ubuntu Pro FIPS-updates 22.04 LTS | linux-gcp-fips | 5.15.0-1079.88+fips1 | USN-7387-2 |
| Ubuntu Pro FIPS-updates 20.04 LTS | linux-aws-fips | 5.4.0-1142.153+fips1 | USN-7392-4 |
| Ubuntu Pro FIPS-updates 20.04 LTS | linux-azure-fips | 5.4.0-1147.154+fips1 | USN-7392-2 |
| Ubuntu Pro FIPS-updates 20.04 LTS | linux-fips | 5.4.0-1116.126 | USN-7393-1 |
| Ubuntu Pro FIPS-updates 20.04 LTS | linux-gcp-fips | 5.4.0-1145.154+fips1 | USN-7392-2 |
| Ubuntu Pro 20.04 LTS | linux-nvidia-tegra-5.15 | 5.15.0-1039.39~20.04.1 | — |
| Ubuntu Pro 18.04 LTS | linux-aws-5.4 | 5.4.0-1142.152~18.04.1 | USN-7401-1 |
| Ubuntu Pro 18.04 LTS | linux-azure-5.4 | 5.4.0-1147.154~18.04.1 | USN-7392-1 |
| Ubuntu Pro 18.04 LTS | linux-gcp-5.4 | 5.4.0-1145.154~18.04.1 | USN-7392-1 |
| Ubuntu Pro 18.04 LTS | linux-hwe-5.4 | 5.4.0-211.231~18.04.1 | USN-7391-1 |
| Ubuntu Pro 18.04 LTS | linux-ibm-5.4 | 5.4.0-1090.95~18.04.1 | USN-7463-1 |
| Ubuntu Pro 18.04 LTS | linux-oracle-5.4 | 5.4.0-1140.149~18.04.1 | USN-7392-1 |
| Ubuntu Pro 18.04 LTS | linux-raspi-5.4 | 5.4.0-1129.142~18.04.1 | USN-7540-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | kernel-64kb +7 | 6.12.0-160000.6.1 | SUSE-SU-2025:21139-1 |
| SLES for SAP 16.0 | kernel-default-base | 6.12.0-160000.6.1.160000.2.4 | SUSE-SU-2025:21139-1 |
| SLES 16.0 | kernel-64kb +7 | 6.12.0-160000.6.1 | SUSE-SU-2025:21179-1, SUSE-SU-2025:21139-1 |
| SLES 16.0 | kernel-default-base | 6.12.0-160000.6.1.160000.2.4 | SUSE-SU-2025:21139-1 |
| SLE Micro 6.2 | kernel-default-base | 6.12.0-160000.6.1.160000.2.4 | SUSE-SU-2025:21074-1 |
| SLE Micro 6.2 | kernel-rt +5 | 6.12.0-160000.6.1 | SUSE-SU-2026:20560-1, SUSE-SU-2025:21074-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 16.0 | kernel-default-base | 6.12.0-160000.6.1.160000.2.4 | openSUSE-SU-2025:20081-1 |
| openSUSE Leap 16.0 | kernel-rt +10 | 6.12.0-160000.6.1 | openSUSE-SU-2025:20081-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | kernel-livepatch-6.1.127-135.201 | 1.0-0.amzn2023 | ALAS2023-2025-823 |
| Amazon Linux 2023 | perf +14 | 6.1.127-135.201.amzn2023 | ALAS2023-2025-823 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | kernel | 6.6.76.1-1 | — |
| Azure Linux 2 (CBL-Mariner) | kernel | 5.15.180.1-1 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 9 | kernel-uek +34 | 6.12.0-101.33.4.3.el10uek | ELSA-2025-20530, ELSA-2025-20480 |
Advisories 47
- USN-7653-1 linux-hwe-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 3, 2026
- USN-7595-1 linux, linux-aws, linux-aws-6.8, linux-gke, linux-gkeop, linux-ibm, linux-lowlatency, linux-lowlatency-hwe-6.8, linux-nvidia, linux-nvidia-6.8, linux-nvidia-lowlatency, linux-oem-6.8 vulnerabilities Ubuntu Security Notices (USN) · Oct 30, 2026
- USN-7539-1 linux-raspi vulnerabilities Ubuntu Security Notices (USN) · Oct 30, 2026
- USN-7540-1 linux-raspi-5.4 vulnerabilities Ubuntu Security Notices (USN) · Oct 30, 2026
- USN-7595-4 linux-oracle, linux-oracle-6.8, linux-raspi vulnerabilities Ubuntu Security Notices (USN) · Oct 30, 2026
- USN-7595-3 linux-raspi-realtime vulnerabilities Ubuntu Security Notices (USN) · Oct 30, 2026
- USN-7459-1 linux-intel-iotg-5.15 vulnerabilities Ubuntu Security Notices (USN) · Oct 30, 2026
- USN-7445-1 linux, linux-aws, linux-gcp, linux-hwe-6.11, linux-lowlatency, linux-lowlatency-hwe-6.11, linux-oem-6.11, linux-oracle, linux-raspi, linux-realtime vulnerabilities Ubuntu Security Notices (USN) · Oct 30, 2026
- USN-7459-2 linux-gcp-5.15 vulnerabilities Ubuntu Security Notices (USN) · Oct 30, 2026
- USN-7448-1 linux-azure, linux-azure-6.11 vulnerabilities Ubuntu Security Notices (USN) · Oct 30, 2026
- USN-7595-5 linux-gcp, linux-gcp-6.8 vulnerabilities Ubuntu Security Notices (USN) · Oct 30, 2026
- USN-7595-2 linux-realtime vulnerabilities Ubuntu Security Notices (USN) · Oct 30, 2026
- USN-7387-1 linux, linux-aws, linux-azure, linux-gcp, linux-gke, linux-gkeop, linux-ibm, linux-intel-iotg, linux-lowlatency, linux-lowlatency-hwe-5.15, linux-nvidia, linux-oracle, linux-oracle-5.15, linux-raspi vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7392-1 linux-azure, linux-azure-5.4, linux-bluefield, linux-gcp, linux-gcp-5.4, linux-ibm, linux-kvm, linux-oracle, linux-oracle-5.4, linux-xilinx-zynqmp vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7387-2 linux-fips, linux-aws-fips, linux-azure-fips, linux-gcp-fips vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7596-2 linux-azure-nvidia vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7458-1 linux-ibm-5.15 vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7596-1 linux-azure, linux-azure-6.8 vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7387-3 linux-realtime, linux-intel-iot-realtime vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7392-2 linux-azure-fips, linux-gcp-fips vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7391-1 linux, linux-hwe-5.4 vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7421-1 linux-azure-5.15, linux-azure-fde-5.15 vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7388-1 linux-aws-5.15, linux-kvm vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7389-1 linux-nvidia-tegra, linux-nvidia-tegra-igx vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7390-1 linux-xilinx-zynqmp vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7413-1 linux-iot vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7407-1 linux-hwe-5.15 vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7463-1 linux-ibm-5.4 vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7393-1 linux-fips vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7401-1 linux-aws-5.4 vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7392-3 linux-aws vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- USN-7392-4 linux-aws-fips vulnerabilities Ubuntu Security Notices (USN) · Oct 29, 2026
- SSA-265688 SSA-265688: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 TM MFP V1.1 Siemens ProductCERT · Oct 13, 2026
- SUSE-SU-2026:20560-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Jul 9, 2026
- ICSA-24-102-01 Siemens SIMATIC S7-1500 TM MFP CISA ICS & IT advisories · May 14, 2026
- openSUSE-SU-2025:20081-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:21179-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:21139-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:21074-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Mar 23, 2026
- DLA-4075-1 linux - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-4076-1 linux-6.1 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- WID-SEC-2025-0362 Linux Kernel: Mehrere Schwachstellen BSI CERT-Bund (WID) · Mar 5, 2026
- ICSA-25-226-07 Siemens Third-Party Components in SINEC OS CISA ICS & IT advisories · Feb 25, 2026
- SSA-355557 SSA-355557: Multiple Vulnerabilities in Third-Party Components in SINEC OS before V3.2 Siemens ProductCERT · Feb 24, 2026
- ELSA-2025-20530 Important: Unbreakable Enterprise kernel security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Aug 18, 2025
- ELSA-2025-20480 Important: Unbreakable Enterprise kernel security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Jul 17, 2025
- ALAS2023-2025-823 Important: kernel security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Mar 10, 2025
References
- https://git.kernel.org/stable/c/95e4f62df23f4df1ce6ef897d44b8e23c260921a
- https://git.kernel.org/stable/c/14984139f1f2768883332965db566ef26db609e7
- https://git.kernel.org/stable/c/15b453db41d36184cf0ccc21e7df624014ab6a1a
- https://git.kernel.org/stable/c/3d41dbf82e10c44e53ea602398ab002baec27e75
- https://git.kernel.org/stable/c/a5cbbea145b400e40540c34816d16d36e0374fbc
- https://git.kernel.org/stable/c/38492f6ee883c7b1d33338bf531a62cff69b4b28
- https://git.kernel.org/stable/c/2f8dea1692eef2b7ba6a256246ed82c365fdc686