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CVE-2026-72164
ocfs2: avoid moving extents to occupied clusters
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem fs/ocfs2. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-72164 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixed | 6.1.180-1 | Update the kernel and reboot. Fixed in 6.1.180-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.100-1 | Update the kernel and reboot. Fixed in 6.12.100-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
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.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
fs/ocfs2/move_extents.c
- What this is
- ORACLE CLUSTER FILESYSTEM 2 (OCFS2)MAINTAINERS section matched on fs/ocfs2/ · ocfs2-devel@lists.linux.dev · Supported
- Kernel module
- ocfs2
Check it on the machine
grep -w CONFIG_OCFS2_FS /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w ocfs2Prints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookworm, trixie, forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- M
- a module where it is built at all; some flavours do not build it
- Build switch
- CONFIG_OCFS2_FS
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-08-15 (2 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.17%, higher than 5.8% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- fs/ocfs2
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 3.0 | 5.10.261 | 3112afebf2a7 |
| 3.0 | 5.15.212 | 35486b291b8f |
| 3.0 | 6.1.178 | 19f7b04924b2 |
| 3.0 | 6.6.145 | e281d892ce58 |
| 3.0 | 6.12.97 | 0d0c5c17b18b |
| 3.0 | 6.18.40 | d5d5a21fb33c |
| 3.0 | 7.1.5 | 4d1953d3aeb4 |
| 3.0 | 7.2 | 22920541c35a |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- Exploitation requires the OCFS2_IOC_MOVE_EXT ioctl on a locally mounted ocfs2 volume via sys_ioctl→vfs_ioctl→ocfs2_ioctl; OCFS2 has no network-facing handler exposing this code path.
- AC:LAttack complexity, low
- The attacker fully controls me_goal and move length on the non-auto path; an occupied goal at the end of an alloc group deterministically bypasses ocfs2_probe_alloc_group() and reaches __ocfs2_move_extent() with no races or external preconditions.
- PR:LPrivileges required, low
- OCFS2_IOC_MOVE_EXT performs no capable() check (unlike FITRIM); any local user with FMODE_WRITE on a regular file on an ocfs2 mount can invoke ioctl(), including root inside a user namespace per kernel CNA guidance.
- UI:NUser interaction, none
- The attacker issues OCFS2_IOC_MOVE_EXT on their own writable fd with crafted parameters; no victim interaction or third-party action is required beyond the enterprise ocfs2 mount already being present.
- S:UScope, unchanged
- Impact is confined to on-disk data corruption and filesystem availability within the same cluster node/kernel authority; it does not cross VM, container, or IOMMU security boundaries.
- C:HConfidentiality impact, high
- __ocfs2_move_extent() copies into clusters still allocated to other inodes, creating cross-file block aliasing on shared cluster storage so later reads through the new extent can return another tenant's or root-owned file contents.
- I:HIntegrity impact, high
- ocfs2_duplicate_clusters_by_page() writes attacker-controlled file data into physical clusters owned by other inodes before the bitmap is updated, enabling arbitrary corruption of files the attacker lacks write permission to on shared OCFS2 storage.
- A:HAvailability impact, high
- Dual allocation and bitmap/extent inconsistency can trigger ocfs2_error(), forcing remount-ro or panic on the node and corrupting shared storage in ways that impair availability for all cluster members until fsck.ocfs2.