CVE-2024-42243

/// Technical description

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

mm/filemap: make MAX_PAGECACHE_ORDER acceptable to xarray

Patch series "mm/filemap: Limit page cache size to that supported by

xarray", v2.

Currently, xarray can't support arbitrary page cache size. More details

can be found from the WARN_ON() statement in xas_split_alloc(). In our

test whose code is attached below, we hit the WARN_ON() on ARM64 system

where the base page size is 64KB and huge page size is 512MB. The issue

was reported long time ago and some discussions on it can be found here

[1].

[1] https://www.spinics.net/lists/linux-xfs/msg75404.html

In order to fix the issue, we need to adjust MAX_PAGECACHE_ORDER to one

supported by xarray and avoid PMD-sized page cache if needed. The code

changes are suggested by David Hildenbrand.

PATCH[1] adjusts MAX_PAGECACHE_ORDER to that supported by xarray

PATCH[2-3] avoids PMD-sized page cache in the synchronous readahead path

PATCH[4] avoids PMD-sized page cach

/// 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