CVE-2026-46175 Linux CVE debrief

Who should care

Linux system administrators using F2FS filesystems, particularly on flash storage devices; embedded systems developers relying on F2FS for robust power-loss recovery; security teams monitoring filesystem integrity issues

Technical summary

The vulnerability exists in F2FS's Foreground Garbage Collection (FGGC) implementation. During node block migration, FGGC does not clear the DENT_BIT_SHIFT (dentry) and fsync marks, unlike Background Garbage Collection (BGGC) which handles this through f2fs_sync_node_pages(). When a sudden power loss occurs after FGGC moves data blocks in synchronous mode without writing a checkpoint, fsck incorrectly reports that an inode has been checkpointed but still has DENT_BIT_SHIFT set. The fix relocates the set/clear logic for fsync and dentry marks into __write_node_folio, ensuring consistent mark handling regardless of GC mode. This prevents fsck from misinterpreting GC-migrated blocks as user fsync operations.

Defensive priority

medium

Recommended defensive actions

• Apply the relevant Linux kernel stable patches when available for your distribution
• Monitor vendor security advisories for kernel updates addressing this F2FS issue
• Run fsck on F2FS filesystems after unexpected shutdowns to verify consistency
• Consider using BGGC mode instead of FGGC if configurable, as BGGC was not affected by this issue
• Review filesystem logs for DENT_BIT_SHIFT related errors after power loss events

Evidence notes

Vulnerability disclosed via Linux kernel stable tree commits on 2026-05-28. The issue was resolved through kernel patches that move fsync and dentry mark handling into __write_node_folio to ensure marks are properly cleared during FGGC node block migration.

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.