CVE-2026-80856

/// Technical description

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

fuse: fix invalidate lock leak on setattr writeback failure

fuse_do_setattr() takes filemap_invalidate_lock() for a DAX truncate

(fault_blocked = true) and releases it at the out:/error: labels. But

when a writeback flush is also needed, a write_inode_now() failure

returns directly and leaks the lock, so any later fault or truncate on

the file stalls on the stale rwsem.

For example, truncate(2) on a setuid file reaches fuse_do_setattr()

with both ATTR_SIZE and ATTR_MODE set:

truncate(2)

└─ do_truncate()

├─ dentry_needs_remove_privs() # S_ISUID

└─ notify_change() # KILL_SUID -> ATTR_MODE

└─ fuse_setattr() # no killpriv:

│ # ia_valid |= ATTR_MODE

└─ fuse_do_setattr()

├─ filemap_invalidate_lock() # IS_DAX && is_truncate

└─ write_inode_now() # is_wb && ATTR_MO

/// 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