CVE-2026-53368f2fs: fix fsck inconsistency caused by incorrect nat_entry flag usage

Official description

In the Linux kernel, the following vulnerability has been resolved: f2fs: fix fsck inconsistency caused by incorrect nat_entry flag usage f2fs_need_dentry_mark() reads nat_entry flags without mutual exclusion with the checkpoint path, which can result in an incorrect inode block marking state. The scenario is as follows: create & write & fsync 'file A' write checkpoint - f2fs_do_sync_file // inline inode - f2fs_write_inode // inode folio is dirty - f2fs_write_checkpoint - f2fs_flush_merged_writes - f2fs_sync_node_pages - f2fs_fsync_node_pages // no dirty node - f2fs_need_inode_block_update // return true - f2fs_fsync_node_pages // inode dirtied - f2fs_need_dentry_mark //return true - f2fs_flush_nat_entries - f2fs_write_checkpoint end - __write_node_folio // inode with DENT_BIT_SHIFT set SPO, "fsck --dry-run" find inode has already checkpointed but still with DENT_BIT_SHIFT set The state observed by f2fs_need_dentry_mark() can differ from the state observed in __write_node_folio() after acquiring sbi->node_write. The root cause is that the semantics of IS_CHECKPOINTED and HAS_FSYNCED_INODE are only guaranteed after the checkpoint write has fully completed. This patch moves set_dentry_mark() into __write_node_folio() and protects it with the sbi->node_write lock.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/bb1275802b482bc5854e434e212589fe253eab22
• https://git.kernel.org/stable/c/270c519bca3a59b6140d176415aff16e4e06f9e3
• https://git.kernel.org/stable/c/bedb710b63ae1bd617e65d0a8cf6cea1200b3753
• https://git.kernel.org/stable/c/b28a83ea4934215b5de906c3ee4fbfbc651573e0
• https://git.kernel.org/stable/c/019f9dda7f66e55eb94cd32e1d3fff5835f73fbc