CVE-2026-72164
Received Received - Intake

OCFS2 Extent Move Heap Overflow in Linux Kernel

Vulnerability report for CVE-2026-72164, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-08-15

Last updated on: 2026-08-15

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: ocfs2: avoid moving extents to occupied clusters For non-auto OCFS2_IOC_MOVE_EXT operations, userspace supplies a physical me_goal. ocfs2_move_extent() initializes new_phys_cpos from that goal and expects ocfs2_probe_alloc_group() to replace it with a free run in the target block group. The probe currently leaves *phys_cpos unchanged if the scan reaches the end of the group without finding a free run. An occupied goal at the last bit can therefore survive the probe and be passed to __ocfs2_move_extent(), which copies file data into a cluster still owned by another inode before the bitmap is updated. When the probe does find a free run, it also subtracts move_len from the ending bit. The start of an N-bit run ending at i is i - N + 1, so the current calculation can report the bit immediately before the free run. Clear *phys_cpos before scanning and use the correct free-run start. Callers already treat a zero result as -ENOSPC, so failed probes no longer continue with an occupied caller-controlled goal.

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Meta Information

Published
2026-08-15
Last Modified
2026-08-15
Generated
2026-08-15
AI Q&A
2026-08-15
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux_kernel ocfs2 *

Helpful Resources

Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a flaw in the OCFS2 file system's extent moving operation. When userspace requests moving file extents, the system may incorrectly use an occupied cluster instead of a free one. This happens because the probing function for free space fails to reset the target position properly, allowing an occupied cluster to be reused. The issue arises when the probe scans for free space but reaches the end without finding any, leaving the original occupied position unchanged.

Impact Analysis

This vulnerability could lead to data corruption or loss. If an attacker exploits this flaw, they might overwrite data in a cluster still owned by another inode, causing file system inconsistencies. This could result in application crashes, file system errors, or even system instability. Users relying on OCFS2 for storage may experience unexpected behavior or data integrity issues.

Mitigation Strategies

Update the Linux kernel to the latest patched version to resolve the OCFS2 extent movement vulnerability. Monitor OCFS2 filesystem operations for unexpected extent movements or data corruption.

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