CVE-2026-98536 Linux CVE debrief

Who should care

Linux kernel maintainers, users, and administrators should assess exposure and verify patched versions to prevent potential hung task detector panics. This includes reviewing Linux kernel versions and configurations, verifying patched versions, and monitoring for BPF or ftrace detach operations during long drain periods. Additionally, operators, platform administrators, and security teams should be aware of the vulnerability and its potential impacts on他们的

Why it matters

A vulnerability in the Linux kernel has been resolved, which could cause a Tasks-RCU quiescent state stall. Linux kernel maintainers and users should assess exposure and verify patched versions.

• Verification of patched Linux kernel versions is required to prevent potential issues.
• Monitoring for BPF or ftrace detach operations during long drain periods is necessary.

Technical summary

The Linux kernel vulnerability causes a Tasks-RCU quiescent state stall due to the `cleanup_offline_cgwbs_workfn()` function not reporting a Tasks-RCU quiescent state during a cgwb drain pass. This can lead to a hung task detector panic. A fix has been implemented by calling cond_resched_tasks_rcu_qs() to report a Tasks-RCU quiescent state per cgwb drain pass, preventing potential hung task detector panics in affected Linux kernel versions. The fix ensures that the drain loop reports a Tasks-RCU quiescent state, addressing the vulnerability.

Defensive priority

Linux kernel maintainers and users should assess exposure and verify patched versions.

Recommended defensive actions

• Assess exposure by checking Linux kernel versions and configurations.
• Verify patched versions with Linux kernel maintainers.
• Monitor for BPF or ftrace detach operations during long drain periods.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The vulnerability was introduced due to a cond_resched() call in the `cleanup_offline_cgwbs_workfn()` function not reporting a Tasks-RCU quiescent state. A fix has been implemented by calling cond_resched_tasks_rcu_qs().

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.