CVE-2026-63812

Technical Description

In the Linux kernel, the following vulnerability has been resolved:

f2fs: fix incorrect FI_NO_EXTENT handling in __destroy_extent_node()

When __destroy_extent_node() sets the inode flag FI_NO_EXTENT, it does

not reset the length of the largest extent to 0 and update the inode

folio. Since modifications to the extent tree are disallowed afterward,

the cached largest extent may become stale. This can trigger the

following error in xfstests generic/388:

F2FS-fs (dm-0): sanity_check_extent_cache: inode (ino=1761) extent info [220057, 57, 6] is incorrect, run fsck to fix

In the f2fs_drop_inode path, __destroy_extent_node() does not need to

guarantee that et->node_cnt is 0, because concurrency with writeback

is expected in this path, and writeback may update the extent cache.

This patch reverts commit ed78aeebef05 ("f2fs: fix node_cnt race between

extent node destroy and writeback"), and remove the unnecessary zero

check of et->node_cnt.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References