CVE-2025-38008: mm/page_alloc: fix race condition in unaccepted memory handling
In the Linux kernel, the following vulnerability has been resolved:
mm/pagealloc: fix race condition in unaccepted memory handling
The page allocator tracks the number of zones that have unaccepted memory using staticbranchenc/dec() and uses that static branch in hot paths to determine if it needs to deal with unaccepted memory.
Borislav and Thomas pointed out that the tracking is racy: operations on staticbranch are not serialized against adding/removing unaccepted pages to/from the zone.
Sanity checks inside staticbranch machinery detects it:
WARNING: CPU: 0 PID: 10 at kernel/jumplabel.c:276 statickeyslowdeccpuslocked+0x8e/0xa0
The comment around the WARN() explains the problem:
/ Warn about the '-1' case though; since that means a decrement is concurrent with a first (0->1) increment. IOW people are trying to disable something that wasn't yet fully enabled. This suggests an ordering problem on the user side. /
The effect of this staticbranch optimization is only visible on microbenchmark.
Instead of adding more complexity around it, remove it altogether.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
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ubuntu/linux-aws-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1046.49~22.04.1 - Upgrade
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ubuntu/linux-azure-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1051.57~22.04.1 - Upgrade
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ubuntu/linux-azure-fde-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1046.53~22.04.1 - Upgrade
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ubuntu/linux-gcp-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1047.50~22.04.2 - Upgrade
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ubuntu/linux-hwe-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-100.100~22.04.1 - Upgrade
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ubuntu/linux-ibm-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1044.44~22.04.1 - Upgrade
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ubuntu/linux-lowlatency-hwe-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-100.100.1~22.04.1 - Upgrade
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ubuntu/linux-nvidia-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1046.49~22.04.1 - Upgrade
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ubuntu/linux-oracle-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1043.44~22.04.1 - Upgrade
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ubuntu/linux-riscv-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-100.100~22.04.1 - Upgrade
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ubuntu/linux-realtime-6.8to a version that resolves this vulnerability.Fixed in 6.8.1-1041.42~22.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 6.8.0-100.100 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 6.8.0-1046.49 - Upgrade
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ubuntu/linux-aws-6.14to a version that resolves this vulnerability.Fixed in 6.14.0-1011.11~24.04.1 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 6.8.0-1046.52 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 6.8.0-1047.50 - Upgrade
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ubuntu/linux-gcp-6.14to a version that resolves this vulnerability.Fixed in 6.14.0-1014.15~24.04.1 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 6.8.0-1043.48 - Upgrade
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ubuntu/linux-gkeopto a version that resolves this vulnerability.Fixed in 6.8.0-1030.33 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 6.8.0-1044.44 - Upgrade
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ubuntu/linux-lowlatencyto a version that resolves this vulnerability.Fixed in 6.8.0-100.100.1 - Upgrade
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ubuntu/linux-nvidiato a version that resolves this vulnerability.Fixed in 6.8.0-1046.49 - Upgrade
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ubuntu/linux-nvidia-lowlatencyto a version that resolves this vulnerability.Fixed in 6.8.0-1046.49.1 - Upgrade
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ubuntu/linux-nvidia-tegrato a version that resolves this vulnerability.Fixed in 6.8.0-1020.20 - Upgrade
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ubuntu/linux-oem-6.14to a version that resolves this vulnerability.Fixed in 6.14.0-1010.10 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 6.8.0-1043.44 - Upgrade
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ubuntu/linux-oracle-6.14to a version that resolves this vulnerability.Fixed in 6.14.0-1011.11~24.04.1 - Upgrade
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ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 6.8.0-1047.51 - Upgrade
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ubuntu/linux-riscv-6.14to a version that resolves this vulnerability.Fixed in 6.14.0-28.28.1~24.04.1 - Upgrade
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ubuntu/linux-xilinxto a version that resolves this vulnerability.Fixed in 6.8.0-1023.24 - Upgrade
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ubuntu/linux-bluefieldto a version that resolves this vulnerability.Fixed in 6.8.0-1016.20 - Upgrade
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ubuntu/linux-raspi-realtimeto a version that resolves this vulnerability.Fixed in 6.8.0-2037.38 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 6.8.1-1041.42 - Upgrade
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ubuntu/linux-realtime-6.14to a version that resolves this vulnerability.Fixed in 6.14.0-1010.10~24.04.1 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1046.49+fips1 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1046.52+fips1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-100.100+fips1 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1047.50+fips1 - Configuration
Remove the static_branch_enc/dec() tracking and associated static-branch optimization used to detect unaccepted memory in hot paths.
Linux kernel mm/page_alloc static_branch tracking for unaccepted memory = disabled
Event History
Frequently Asked Questions
What level of access is required to exploit this issue?
The CVSS vector indicates that an attacker needs local access and low privileges. No user interaction is required, but exploitation has high attack complexity.
What is the security impact if exploitation succeeds?
The documented impact is availability only, with a high availability impact. The CVSS vector reports no confidentiality or integrity impact.
How can I remediate this vulnerability?
Apply a patch for the Linux kernel. The available fixes remove the static-branch optimization used to track zones with unaccepted memory, eliminating the race condition.