CVE-2024-57942

/// Technical description

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

netfs: Fix ceph copy to cache on write-begin

At the end of netfs_unlock_read_folio() in which folios are marked

appropriately for copying to the cache (either with by being marked dirty

and having their private data set or by having PG_private_2 set) and then

unlocked, the folio_queue struct has the entry pointing to the folio

cleared. This presents a problem for netfs_pgpriv2_write_to_the_cache(),

which is used to write folios marked with PG_private_2 to the cache as it

expects to be able to trawl the folio_queue list thereafter to find the

relevant folios, leading to a hang.

Fix this by not clearing the folio_queue entry if we're going to do the

deprecated copy-to-cache. The clearance will be done instead as the folios

are written to the cache.

This can be reproduced by starting cachefiles, mounting a ceph filesystem

with "-o fsc" and writing to it.

/// 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