CVE-2024-57924

/// Technical description

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

fs: relax assertions on failure to encode file handles

Encoding file handles is usually performed by a filesystem >encode_fh()

method that may fail for various reasons.

The legacy users of exportfs_encode_fh(), namely, nfsd and

name_to_handle_at(2) syscall are ready to cope with the possibility

of failure to encode a file handle.

There are a few other users of exportfs_encode_{fh,fid}() that

currently have a WARN_ON() assertion when ->encode_fh() fails.

Relax those assertions because they are wrong.

The second linked bug report states commit 16aac5ad1fa9 ("ovl: support

encoding non-decodable file handles") in v6.6 as the regressing commit,

but this is not accurate.

The aforementioned commit only increases the chances of the assertion

and allows triggering the assertion with the reproducer using overlayfs,

inotify and drop_caches.

Triggering this assertion was always possible with other filesystems and

other reas

/// 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