CVE-2026-74318 Linux CVE debrief

Who should care

Linux kernel developers and administrators using the btrfs file system with the flushoncommit option should assess exposure and apply the patch to prevent deadlocks. They should also verify that the fix is applied and test for deadlocks, and monitor for potential issues with btrfs file system and flushoncommit option. Additionally, they should review compensating controls for exposed systems and track exceptions, retest remediated assets, and close theitem

Why it matters

A deadlock vulnerability in the Linux kernel's btrfs file system requires attention from developers and administrators to prevent potential denial of service and ensure system stability.

• Potential denial of service due to deadlock
• Verification of fix required to prevent deadlocks
• Update and testing of btrfs file system configurations

Technical summary

The Linux kernel's btrfs file system has a deadlock vulnerability when using the flushoncommit option. The issue occurs when cloning an inline extent with a non-zero offset, causing a deadlock between reflink and transaction commit. The fix ensures that i_size is updated when copying an inline extent's data into the destination file, preventing potential denial of service and ensuring system stability. This vulnerability requires attention from developers and administrators to prevent deadlocks and ensure system stability.

Defensive priority

Medium

Recommended defensive actions

• Review and apply the patch to update i_size when cloning inline extents
• Verify that the fix is applied and test for deadlocks
• Monitor for potential issues with btrfs file system and flushoncommit option
• Perform thorough testing of btrfs file system configurations
• 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

Evidence notes

The issue was reported by syzbot and fixed by ensuring that i_size is updated when copying an inline extent's data into the destination file. The fix addresses the deadlock between reflink and transaction commit when using flushoncommit.

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.