UBUNTU-CVE-2025-68780: Low severity ubuntu/linux-aws vulnerability
In the Linux kernel, the following vulnerability has been resolved: sched/deadline: only set freecpus for online runqueues Commit 16b269436b72 ("sched/deadline: Modify cpudl::freecpus to reflect rd->online") introduced the cpudlset/clearfreecpu functions to allow the cpudl::freecpus mask to be manipulated by the deadline scheduler class rqon/offline callbacks so the mask would also reflect this state. Commit 9659e1eeee28 ("sched/deadline: Remove cpuactivemask from cpudlfind()") removed the check of the cpuactivemask to save some processing on the premise that the cpudl::freecpus mask already reflected the runqueue online state. Unfortunately, there are cases where it is possible for the cpudlclear function to set the freecpus bit for a CPU when the deadline runqueue is offline. When this occurs while a CPU is connected to the default root domain the flag may retain the bad state after the CPU has been unplugged. Later, a different CPU that is transitioning through the default root domain may push a deadline task to the powered down CPU when cpudlfind sees its freecpus bit is set. If this happens the task will not have the opportunity to run. One example is outlined here: https://lore.kernel.org/lkml/20250110233010.2339521-1-opendmb@gmail.com Another occurs when the last deadline task is migrated from a CPU that has an offlined runqueue. The dequeuetask member of the deadline scheduler class will eventually call cpudlclear and set the freecpus bit for the CPU. This commit modifies the cpudlclear function to be aware of the online state of the deadline runqueue so that the freecpus mask can be updated appropriately. It is no longer necessary to manage the mask outside of the cpudlset/clear functions so the cpudlset/clearfreecpu functions are removed. In addition, since the freecpus mask is now only updated under the cpudl lock the code was changed to use the non-atomic cpumask functions.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linux-aws-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1103.110~20.04.1 - Upgrade
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ubuntu/linux-azure-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1110.119~20.04.1 - Upgrade
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ubuntu/linux-gcp-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1103.112~20.04.1 - Upgrade
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ubuntu/linux-hwe-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-173.183~20.04.1 - Upgrade
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ubuntu/linux-ibm-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1097.100~20.04.1 - Upgrade
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ubuntu/linux-intel-iotg-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1098.104~20.04.1 - Upgrade
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ubuntu/linux-lowlatency-hwe-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-173.183~20.04.1 - Upgrade
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ubuntu/linux-nvidia-tegra-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1055.55~20.04.1 - Upgrade
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ubuntu/linux-oracle-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1100.106~20.04.1 - Upgrade
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ubuntu/linux-riscv-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1097.101~20.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 5.15.0-173.183 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 5.15.0-1103.110 - Upgrade
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ubuntu/linux-aws-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1052.55~22.04.1 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 5.15.0-1109.118 - Upgrade
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ubuntu/linux-azure-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1059.65~22.04.1 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 5.15.0-1109.118.1 - Upgrade
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ubuntu/linux-azure-fde-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1058.65~22.04.1 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 5.15.0-1103.112 - Upgrade
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ubuntu/linux-gcp-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1054.57~22.04.1 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 5.15.0-1099.105 - Upgrade
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ubuntu/linux-gkeopto a version that resolves this vulnerability.Fixed in 5.15.0-1086.94 - Upgrade
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ubuntu/linux-hwe-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-110.110~22.04.1 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 5.15.0-1097.100 - Upgrade
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ubuntu/linux-ibm-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1051.51~22.04.1 - Upgrade
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ubuntu/linux-intel-iotgto a version that resolves this vulnerability.Fixed in 5.15.0-1098.104 - Upgrade
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ubuntu/linux-kvmto a version that resolves this vulnerability.Fixed in 5.15.0-1095.100 - Upgrade
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ubuntu/linux-lowlatencyto a version that resolves this vulnerability.Fixed in 5.15.0-173.183 - Upgrade
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ubuntu/linux-lowlatency-hwe-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-110.110.1~22.04.1 - Upgrade
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ubuntu/linux-nvidiato a version that resolves this vulnerability.Fixed in 5.15.0-1098.99 - Upgrade
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ubuntu/linux-nvidia-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1051.54~22.04.1 - Upgrade
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ubuntu/linux-nvidia-tegrato a version that resolves this vulnerability.Fixed in 5.15.0-1055.55 - Upgrade
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ubuntu/linux-nvidia-tegra-igxto a version that resolves this vulnerability.Fixed in 5.15.0-1044.44 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 5.15.0-1100.106 - Upgrade
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ubuntu/linux-oracle-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1049.50~22.04.1 - Upgrade
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ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 5.15.0-1097.100 - Upgrade
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ubuntu/linux-riscv-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-110.110~22.04.1 - Upgrade
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ubuntu/linux-xilinx-zynqmpto a version that resolves this vulnerability.Fixed in 5.15.0-1067.71 - Upgrade
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ubuntu/linux-bluefieldto a version that resolves this vulnerability.Fixed in 5.15.0-1086.88 - Upgrade
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ubuntu/linux-intel-iot-realtimeto a version that resolves this vulnerability.Fixed in 5.15.0-1094.96 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 5.15.0-1102.111 - Upgrade
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ubuntu/linux-realtime-6.8to a version that resolves this vulnerability.Fixed in 6.8.1-1047.48~22.04.1 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-1103.110+fips1 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-1109.118+fips1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-173.183+fips1 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-1103.112+fips1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 6.8.0-110.110 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 6.8.0-1052.55 - Upgrade
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ubuntu/linux-aws-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1012.12~24.04.1 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 6.8.0-1054.60 - Upgrade
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ubuntu/linux-azure-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1013.13~24.04.1 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 6.8.0-1058.65 - Upgrade
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ubuntu/linux-azure-nvidiato a version that resolves this vulnerability.Fixed in 6.8.0-1039.42 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 6.8.0-1054.57 - Upgrade
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ubuntu/linux-gcp-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1012.12~24.04.1 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 6.8.0-1050.56 - Upgrade
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ubuntu/linux-gkeopto a version that resolves this vulnerability.Fixed in 6.8.0-1037.40 - Upgrade
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ubuntu/linux-hwe-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-22.22~24.04.1 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 6.8.0-1051.51 - Upgrade
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ubuntu/linux-lowlatencyto a version that resolves this vulnerability.Fixed in 6.8.0-110.110.1 - Upgrade
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ubuntu/linux-nvidiato a version that resolves this vulnerability.Fixed in 6.8.0-1051.54 - Upgrade
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ubuntu/linux-nvidia-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1018.18 - Upgrade
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ubuntu/linux-nvidia-lowlatencyto a version that resolves this vulnerability.Fixed in 6.8.0-1051.54.1 - Upgrade
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ubuntu/linux-nvidia-tegrato a version that resolves this vulnerability.Fixed in 6.8.0-1022.22 - Upgrade
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ubuntu/linux-oem-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1020.20 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 6.8.0-1049.50 - Upgrade
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ubuntu/linux-oracle-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1011.11~24.04.1 - Upgrade
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ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 6.8.0-1052.56 - Upgrade
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ubuntu/linux-riscv-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-22.22.1~24.04.1 - Upgrade
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ubuntu/linux-xilinxto a version that resolves this vulnerability.Fixed in 6.8.0-1028.29 - Upgrade
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ubuntu/linux-bluefieldto a version that resolves this vulnerability.Fixed in 6.8.0-1017.21 - Upgrade
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ubuntu/linux-raspi-realtimeto a version that resolves this vulnerability.Fixed in 6.8.0-2042.43 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 6.8.1-1047.48 - Upgrade
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ubuntu/linux-realtime-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1010.11~24.04.1 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1052.55+fips1 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1053.59+fips1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-110.110+fips2 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1054.57+fips1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 6.17.0-22.22 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 6.17.0-1012.12 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 6.17.0-1013.13 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 6.17.0-1012.12 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 6.17.0-1011.11 - Upgrade
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ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 6.17.0-1013.13 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 6.17.0-1010.11 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 6.17.0-22.22.1
Event History
Frequently Asked Questions
What systems are most likely to be affected in practice?
Systems using the Linux deadline scheduler with CPU hotplug or power-down activity are the relevant exposure scenario. The failure involves CPUs connected to the default root domain and an offline deadline runqueue retaining an incorrect free-CPU state.
What conditions are required for the scheduling failure?
A free_cpus bit must be set for a CPU whose deadline runqueue is offline, and that bad state must persist after the CPU is unplugged. A later CPU transition through the default root domain can then cause a deadline task to be pushed to the powered-down CPU.
What is the operational impact if the issue occurs?
A deadline-scheduled task can be assigned to a powered-down CPU and will not get an opportunity to run. The provided information describes a task scheduling/availability failure rather than code execution or privilege escalation.
Which Ubuntu kernel package families are listed as affected?
The listed package families are linux, linux-aws, linux-azure, linux-gcp, linux-fips, linux-aws-fips, linux-azure-fips, and linux-gcp-fips.