Description
In the Linux kernel, the following vulnerability has been resolved:
sched/rt: Skip currently executing CPU in rto_next_cpu()
CPU0 becomes overloaded when hosting a CPU-bound RT task, a non-CPU-bound
RT task, and a CFS task stuck in kernel space. When other CPUs switch from
RT to non-RT tasks, RT load balancing (LB) is triggered; with
HAVE_RT_PUSH_IPI enabled, they send IPIs to CPU0 to drive the execution
of rto_push_irq_work_func. During push_rt_task on CPU0,
if next_task->prio < rq->donor->prio, resched_curr() sets NEED_RESCHED
and after the push operation completes, CPU0 calls rto_next_cpu().
Since only CPU0 is overloaded in this scenario, rto_next_cpu() should
ideally return -1 (no further IPI needed).
However, multiple CPUs invoking tell_cpu_to_push() during LB increments
rd->rto_loop_next. Even when rd->rto_cpu is set to -1, the mismatch between
rd->rto_loop and rd->rto_loop_next forces rto_next_cpu() to restart its
search from -1. With CPU0 remaining overloaded (satisfying rt_nr_migratory
&& rt_nr_total > 1), it gets reselected, causing CPU0 to queue irq_work to
itself and send self-IPIs repeatedly. As long as CPU0 stays overloaded and
other CPUs run pull_rt_tasks(), it falls into an infinite self-IPI loop,
which triggers a CPU hardlockup due to continuous self-interrupts.
The trigging scenario is as follows:
cpu0 cpu1 cpu2
pull_rt_task
tell_cpu_to_push
<------------irq_work_queue_on
rto_push_irq_work_func
push_rt_task
resched_curr(rq) pull_rt_task
rto_next_cpu tell_cpu_to_push
<-------------------------- atomic_inc(rto_loop_next)
rd->rto_loop != next
rto_next_cpu
irq_work_queue_on
rto_push_irq_work_func
Fix redundant self-IPI by filtering the initiating CPU in rto_next_cpu().
This solution has been verified to effectively eliminate spurious self-IPIs
and prevent CPU hardlockup scenarios.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Linux | Linux | 4.4.103 – < 4.5, 4.9.66 – < 4.10, 4.14.3 – < 4.15, 4.15 | 4.5 |
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 | 6.18.14-1 | — |
| Debian 13 | linux | 6.12.85-1 | — |
| Debian 12 | linux | 6.1.170-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Nvidia-BlueField 24.04 LTS | linux-bluefield | 6.8.0-1026.30 | — |
| Ubuntu Nvidia-BlueField 22.04 LTS | linux-bluefield | 5.15.0-1096.98 | — |
| Ubuntu 25.10 | linux +8 | No fix yet | — |
| Ubuntu 24.04 LTS | linux | 6.8.0-134.134 | USN-8492-1 |
| Ubuntu 24.04 LTS | linux-aws | 6.8.0-1060.63 | USN-8492-1 |
| Ubuntu 24.04 LTS | linux-azure | 6.8.0-1063.71 | USN-8606-1 |
| Ubuntu 24.04 LTS | linux-azure-fde | 6.8.0-1062.69 | USN-8607-1 |
| Ubuntu 24.04 LTS | linux-azure-nvidia | 6.8.0-1039.42 | — |
| Ubuntu 24.04 LTS | linux-gcp | 6.8.0-1063.69 | USN-8492-1 |
| Ubuntu 24.04 LTS | linux-gke | 6.8.0-1058.64 | USN-8492-2 |
| Ubuntu 24.04 LTS | linux-gkeop | 6.8.0-1045.48 | USN-8492-2 |
| Ubuntu 24.04 LTS | linux-ibm | 6.8.0-1060.61 | USN-8492-1 |
| Ubuntu 24.04 LTS | linux-lowlatency | 6.8.0-134.134.1 | USN-8497-1 |
| Ubuntu 24.04 LTS | linux-nvidia | 6.8.0-1058.61 | USN-8492-1 |
| Ubuntu 24.04 LTS | linux-nvidia-lowlatency | 6.8.0-1058.61.1 | USN-8492-2 |
| Ubuntu 24.04 LTS | linux-nvidia-tegra | 6.8.0-1029.30 | USN-8498-1 |
| Ubuntu 24.04 LTS | linux-oracle | 6.8.0-1057.58 | USN-8492-1 |
| Ubuntu 24.04 LTS | linux-raspi | 6.8.0-1060.64 | USN-8492-4 |
| Ubuntu 24.04 LTS | linux-riscv +26 | No fix yet | — |
| Ubuntu 24.04 LTS | linux-xilinx | 6.8.0-1032.33 | USN-8499-1 |
| Ubuntu 22.04 LTS | linux | 5.15.0-186.196 | USN-8575-1 |
| Ubuntu 22.04 LTS | linux-aws | 5.15.0-1112.119 | USN-8575-2 |
| Ubuntu 22.04 LTS | linux-aws-6.8 | 6.8.0-1060.63~22.04.1 | USN-8492-2 |
| Ubuntu 22.04 LTS | linux-azure +1 | 5.15.0-1117.126 | USN-8610-1, USN-8575-3 |
| Ubuntu 22.04 LTS | linux-azure-6.8 | 6.8.0-1063.71~22.04.1 | USN-8606-1 |
| Ubuntu 22.04 LTS | linux-azure-fde-6.8 | 6.8.0-1062.69~22.04.1 | USN-8609-1 |
| Ubuntu 22.04 LTS | linux-gcp | 5.15.0-1112.122 | USN-8575-1 |
| Ubuntu 22.04 LTS | linux-gcp-6.8 | 6.8.0-1063.69~22.04.1 | USN-8492-2 |
| Ubuntu 22.04 LTS | linux-gke | 5.15.0-1108.114 | USN-8575-1 |
| Ubuntu 22.04 LTS | linux-gkeop | 5.15.0-1095.103 | USN-8575-1 |
| Ubuntu 22.04 LTS | linux-hwe-6.8 | 6.8.0-136.136~22.04.1 | USN-8619-1 |
| Ubuntu 22.04 LTS | linux-ibm | 5.15.0-1106.110 | USN-8575-2 |
| Ubuntu 22.04 LTS | linux-ibm-6.8 | 6.8.0-1060.61~22.04.1 | USN-8492-2 |
| Ubuntu 22.04 LTS | linux-intel-iotg | 5.15.0-1107.113 | USN-8620-4 |
| Ubuntu 22.04 LTS | linux-kvm | 5.15.0-1104.109 | USN-8575-1 |
| Ubuntu 22.04 LTS | linux-lowlatency | 5.15.0-184.194 | USN-8575-1 |
| Ubuntu 22.04 LTS | linux-lowlatency-hwe-6.8 | 6.8.0-134.134.1~22.04.1 | USN-8497-1 |
| Ubuntu 22.04 LTS | linux-nvidia | 5.15.0-1107.108 | USN-8575-2 |
| Ubuntu 22.04 LTS | linux-nvidia-6.8 | 6.8.0-1058.61~22.04.1 | USN-8492-1 |
| Ubuntu 22.04 LTS | linux-nvidia-tegra | 5.15.0-1064.66 | USN-8576-2 |
| Ubuntu 22.04 LTS | linux-nvidia-tegra-igx | 5.15.0-1053.53 | USN-8576-2 |
| Ubuntu 22.04 LTS | linux-oracle | 5.15.0-1109.115 | USN-8575-3 |
| Ubuntu 22.04 LTS | linux-oracle-6.8 | 6.8.0-1057.58~22.04.1 | USN-8492-2 |
| Ubuntu 22.04 LTS | linux-raspi | 5.15.0-1106.109 | USN-8668-2 |
| Ubuntu 22.04 LTS | linux-riscv +32 | No fix yet | — |
| Ubuntu 22.04 LTS | linux-riscv-6.8 | 6.8.0-134.134~22.04.1 | — |
| Ubuntu 22.04 LTS | linux-xilinx-zynqmp | 5.15.0-1075.79 | USN-8575-1 |
Show 18 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | linux-gke +28 | No fix yet | — |
| Ubuntu 18.04 LTS | linux-gcp +14 | No fix yet | — |
| Ubuntu 16.04 LTS | linux-hwe-edge | No fix yet | — |
| Ubuntu Pro Realtime 24.04 LTS | linux-raspi-realtime | 6.8.0-2049.50 | USN-8492-3 |
| Ubuntu Pro Realtime 24.04 LTS | linux-realtime | 6.8.1-1055.56 | USN-8492-1 |
| Ubuntu Pro Realtime 24.04 LTS | linux-realtime-6.14 +1 | No fix yet | — |
| Ubuntu Pro Realtime 22.04 LTS | linux-intel-iot-realtime | 5.15.0-1104.106 | USN-8620-3 |
| Ubuntu Pro Realtime 22.04 LTS | linux-realtime | 5.15.0-1111.120 | USN-8575-1 |
| Ubuntu Pro Realtime 22.04 LTS | linux-realtime-6.8 | 6.8.1-1055.56~22.04.1 | USN-8492-1 |
| Ubuntu Pro FIPS 20.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS 18.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS 16.04 LTS | linux-fips | No fix yet | — |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-aws-fips | 6.8.0-1060.63+fips1 | USN-8492-1 |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-azure-fips | 6.8.0-1062.69+fips1 | USN-8492-5 |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-fips | 6.8.0-134.134+fips1 | USN-8492-5 |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-gcp-fips | 6.8.0-1063.69+fips1 | USN-8492-1 |
| Ubuntu Pro FIPS-updates 22.04 LTS | linux-aws-fips | 5.15.0-1112.119+fips1 | USN-8575-2 |
| Ubuntu Pro FIPS-updates 22.04 LTS | linux-azure-fips | 5.15.0-1117.126+fips1 | USN-8620-2 |
| Ubuntu Pro FIPS-updates 22.04 LTS | linux-fips | 5.15.0-186.196+fips1 | USN-8575-2 |
| Ubuntu Pro FIPS-updates 22.04 LTS | linux-gcp-fips | 5.15.0-1112.122+fips1 | USN-8575-1 |
| Ubuntu Pro FIPS-updates 20.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro FIPS-updates 16.04 LTS | linux-fips | No fix yet | — |
| Ubuntu Pro FIPS-preview 22.04 LTS | linux-fips +3 | No fix yet | — |
| Ubuntu Pro 20.04 LTS | linux +10 | No fix yet | — |
| Ubuntu Pro 20.04 LTS | linux-aws-5.15 | 5.15.0-1112.119~20.04.1 | USN-8575-2 |
| Ubuntu Pro 20.04 LTS | linux-azure-5.15 | 5.15.0-1117.126~20.04.1 | USN-8620-1 |
| Ubuntu Pro 20.04 LTS | linux-azure-fde-5.15 | 5.15.0-1117.126~20.04.2 | USN-8620-1 |
| Ubuntu Pro 20.04 LTS | linux-gcp-5.15 | 5.15.0-1112.122~20.04.1 | USN-8668-1 |
| Ubuntu Pro 20.04 LTS | linux-hwe-5.15 | 5.15.0-186.196~20.04.1 | USN-8575-1 |
| Ubuntu Pro 20.04 LTS | linux-ibm-5.15 +1 | 5.15.0-1106.110~20.04.1 | USN-8597-1 |
| Ubuntu Pro 20.04 LTS | linux-intel-iotg-5.15 | 5.15.0-1107.113~20.04.1 | USN-8620-3 |
| Ubuntu Pro 20.04 LTS | linux-lowlatency-hwe-5.15 | 5.15.0-184.194~20.04.1 | USN-8575-1 |
| Ubuntu Pro 20.04 LTS | linux-nvidia-tegra-5.15 | 5.15.0-1064.66~20.04.1 | USN-8576-1 |
| Ubuntu Pro 20.04 LTS | linux-oracle-5.15 | 5.15.0-1109.115~20.04.1 | USN-8620-1 |
| Ubuntu Pro 18.04 LTS | linux +12 | No fix yet | — |
| Ubuntu Pro 16.04 LTS | linux +7 | No fix yet | — |
| Ubuntu Pro 14.04 LTS | linux-aws +2 | No fix yet | — |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 9 | rv +73 | 5.14.0-687.56.1.el9_8 | ALSA-2026:77689 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | kernel-64kb +4 | 6.4.0-150700.53.73.2 | SUSE-SU-2026:3166-1 |
| SLES 15 SP7 | kernel-default-base | 6.4.0-150700.53.73.2.150700.17.41.4 | SUSE-SU-2026:3166-1 |
| SLES 15 SP7 | kernel-docs +2 | 6.4.0-150700.53.73.1 | SUSE-SU-2026:3166-1 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLE Micro 6.1 | kernel-rt +4 | 6.4.0-51.1 | SUSE-SU-2026:23194-1, SUSE-SU-2026:23193-1 |
| SLE Micro 6.0 | kernel-rt +4 | 6.4.0-51.1 | SUSE-SU-2026:23244-1, SUSE-SU-2026:23241-1 |
| SLE Live Patching 15 SP7 | kernel-default | 6.4.0-150700.53.73.2 | SUSE-SU-2026:3166-1 |
| SLE Live Patching 15 SP7 | kernel-livepatch-SLE15-SP7-RT_Update_18 | 1-150700.1.5.1 | SUSE-SU-2026:3130-1 |
| SLE Live Patching 15 SP7 | kernel-livepatch-SLE15-SP7_Update_19 | 1-150700.15.3.4 | SUSE-SU-2026:3166-1 |
| SUSE Real Time Module 15 SP7 | kernel-rt +2 | 6.4.0-150700.7.67.1 | SUSE-SU-2026:3130-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | kernel-livepatch-6.12.77-99.140 +2 | 1:1.0-0.amzn2023 | ALAS2023-2026-1544, ALAS2023-2026-1543, ALAS2023-2026-1514 |
| Amazon Linux 2023 | perf +14 | 1:6.1.166-197.305.amzn2023 | ALAS2023-2026-1544 |
| Amazon Linux 2023 | perf6.12 +14 | 1:6.12.77-99.140.amzn2023 | ALAS2023-2026-1543 |
| Amazon Linux 2023 | perf6.18 +14 | 1:6.18.15-14.217.amzn2023 | ALAS2023-2026-1514 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 9 | kernel-uek +34 | 6.12.0-204.92.4.2.el10uek | ELSA-2026-50372 |
Advisories 37
- WID-SEC-2026-1700 Linux Kernel: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 12, 2026
- USN-8575-1 linux, linux-gcp, linux-gcp-fips, linux-gke, linux-gkeop, linux-hwe-5.15, linux-kvm, linux-lowlatency, linux-lowlatency-hwe-5.15, linux-realtime, linux-xilinx-zynqmp vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8575-2 linux-aws, linux-aws-5.15, linux-aws-fips, linux-fips, linux-ibm, linux-nvidia vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8620-1 linux-azure-5.15, linux-azure-fde-5.15, linux-oracle-5.15 vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8620-3 linux-intel-iot-realtime, linux-intel-iotg-5.15 vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8668-2 linux-raspi vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8610-1 linux-azure-fde vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8575-3 linux-azure, linux-oracle vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8668-1 linux-gcp-5.15 vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8576-1 linux-nvidia-tegra-5.15 vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8576-2 linux-nvidia-tegra, linux-nvidia-tegra-igx vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8620-4 linux-intel-iotg vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8620-2 linux-azure-fips vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8606-1 linux-azure, linux-azure-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
- USN-8607-1 linux-azure-fde vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
- USN-8597-1 linux-ibm-5.15 vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
- USN-8619-1 linux-hwe-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
- USN-8609-1 linux-azure-fde-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
- USN-8499-1 linux-xilinx vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
- USN-8497-1 linux-lowlatency, linux-lowlatency-hwe-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 7, 2026
- USN-8492-1 linux, linux-aws, linux-aws-fips, linux-gcp, linux-gcp-fips, linux-ibm, linux-nvidia, linux-nvidia-6.8, linux-oracle, linux-realtime, linux-realtime-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 6, 2026
- USN-8492-2 linux-aws-6.8, linux-gcp-6.8, linux-gke, linux-gkeop, linux-ibm-6.8, linux-nvidia-lowlatency, linux-oracle-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 6, 2026
- USN-8498-1 linux-nvidia-tegra vulnerabilities Ubuntu Security Notices (USN) · Nov 6, 2026
- USN-8492-3 linux-raspi-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 6, 2026
- USN-8492-5 linux-azure-fips, linux-fips vulnerabilities Ubuntu Security Notices (USN) · Nov 6, 2026
- USN-8492-4 linux-raspi vulnerabilities Ubuntu Security Notices (USN) · Nov 6, 2026
- ALSA-2026:77689 Important: kernel security, bug fix, and enhancement update AlmaLinux Security Advisories · Oct 29, 2026
- SUSE-SU-2026:23244-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 27, 2026
- SUSE-SU-2026:23241-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 27, 2026
- SUSE-SU-2026:23193-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 26, 2026
- SUSE-SU-2026:23194-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 26, 2026
- SUSE-SU-2026:3166-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Jul 22, 2026
- SUSE-SU-2026:3130-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Jul 21, 2026
- ELSA-2026-50372 Important: Unbreakable Enterprise kernel security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Jul 2, 2026
- ALAS2023-2026-1514 Important: kernel6.18 security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Jun 16, 2026
- ALAS2023-2026-1543 Important: kernel6.12 security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Jun 16, 2026
- ALAS2023-2026-1544 Important: kernel security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Jun 16, 2026
References
- https://git.kernel.org/stable/c/d57d0746276a88ea43a2cc62b849fd8a95e32e41
- https://git.kernel.org/stable/c/3b3c672a66db3de3b40f8a7057864bc1f874ede3
- https://git.kernel.org/stable/c/16ca9f3117e9a294646c897daf08a5ab546c711b
- https://git.kernel.org/stable/c/8ad5577b2d4acfd83f03d97a0aece2d18aac5f07
- https://git.kernel.org/stable/c/a6a73403733e86748421f2eeaf028c85683ef896
- https://git.kernel.org/stable/c/52aeb1e07ec223caf212f036817976c98d2aa250
- https://git.kernel.org/stable/c/9f25edc5a20cb52a5abbf25f0724bb4732b81801
- https://git.kernel.org/stable/c/94894c9c477e53bcea052e075c53f89df3d2a33e