Executive brief
A vulnerability was identified in the Linux kernel's memory management subsystem. The issue occurs when the system attempts to clean up memory mappings (VMAs) that are not yet fully established, particularly when using 'stacked' drivers like overlayfs. While this primarily results in kernel warnings and internal state inconsistencies, it represents a flaw in how the system handles memory allocation errors.
Technical details
A vulnerability in mm/vma.c and mm/util.c of the Linux kernel involves an incorrect VMA cleanup procedure. When mmap_prepare() is invoked from the mmap() hook of stacked drivers (e.g., overlayfs), it may receive a detached, not-fully-established VMA pointer. If an error occurs, the system attempts to unmap this VMA, triggering warnings in vma_mark_detached() because the VMA is already in a detached state. The fix introduces a compatibility flag to ensure that the mmap() handler handles cleanup in these specific scenarios instead of mmap_action_complete() attempting a redundant and problematic unmap operation.
Affected products
- Linux Linux 6.19, 7.0.9, 7.1
Timeline
- 2026-04-21: disclosed: Initial patch submission by Lorenzo Stoakes
- 2026-05-17: patched: Patch committed to stable tree
- 2026-07-19: advisory: CVE-2026-53373 published