Junglewise Threat Intelligence

CVE-2024-57924: Linux Kernel reachable assertion in file handle encoding

CVE-2024-57924 · Severity: medium · CVSS 5.5 · Published 2025-01-19

Technologies: Linux Kernel. Vendors: Linux.

Executive brief

A vulnerability in the Linux kernel's file system handling could allow a local user to trigger a system warning or crash. The issue occurs when the system incorrectly handles failures while generating unique identifiers for files, particularly when using specific file system features like OverlayFS or inotify. This could lead to a denial of service, impacting the availability of the affected system.

Technical details

A reachable assertion vulnerability (CWE-617) exists in the Linux kernel's file system (fs) layer. The issue stems from 'WARN_ON()' assertions in 'exportfs_encode_fh()' and 'exportfs_encode_fid()' that are triggered when the '->encode_fh()' method fails. While legacy users like nfsd handle these failures gracefully, other components like inotify and OverlayFS (specifically during copy-up operations) contained assertions that assumed encoding would always succeed. A local attacker can trigger these assertions using a combination of OverlayFS, inotify, and memory cache manipulation (drop_caches), leading to a kernel oops or denial of service. The fix involves relaxing these assertions to allow the kernel to handle encoding failures without triggering a panic.

Affected products

  • Linux Linux Kernel up to 6.1.151, 6.2 to 6.6.74, 6.7 to 6.12.10, 6.13-rc1 to 6.13-rc6

Timeline

  • 2025-01-19: disclosed
  • 2025-01-19: advisory

References

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