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CVE-2026-74349
ocfs2: reject FITRIM ranges shorter than a cluster
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-2026-74349 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
ocfs2_trim_mainbm() trims the global bitmap in cluster units, but its too-short range validation only checks sb->s_blocksize. On filesystems with a cluster size larger than the block size, a FITRIM range that is at least one block but shorter than one cluster is accepted and shifted down to len == 0. The later start + len - 1 and len -= ... arithmetic then underflows and can drive trimming past the requested range. Reject ranges shorter than s_clustersize instead. That preserves the existing -EINVAL behavior for requests that cannot discard even one allocation unit and keeps zero-cluster trims out of the group walk.
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/alloc.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
- 7.1 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.13%, higher than 2.1% 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 |
|---|---|---|
| 3.14 | 5.10.261 | d903d59c0315 |
| 3.14 | 5.15.212 | 441abb77222f |
| 3.14 | 6.1.178 | e652d0f5108e |
| 3.14 | 6.6.145 | 346314bb0cc2 |
| 3.14 | 6.12.97 | 06c0a0431b98 |
| 3.14 | 6.18.40 | 3fa7139b5f42 |
| 3.14 | 7.1.5 | 2c13e02592b9 |
| 3.14 | 7.2 | ca1afd88f5ea |
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 a local FITRIM ioctl on an open OCFS2 mount (typically via fstrim or ioctl on the mountpoint); there is no network-facing OCFS2 handler or remote protocol path to this code.
- AC:LAttack complexity, low
- An attacker with the required privileges can reliably trigger the bug by supplying a FITRIM range at least one block long but shorter than one cluster, which is common when OCFS2 cluster size exceeds the 4K block size.
- PR:LPrivileges required, low
- The FITRIM handler explicitly requires capable(CAP_SYS_ADMIN) before calling ocfs2_trim_fs(); per kernel CNA guidance this maps to Low because CAP_SYS_ADMIN can be held by root inside a user namespace.
- UI:NUser interaction, none
- No victim interaction is required; the privileged attacker directly issues the FITRIM ioctl with crafted range parameters to trigger the faulty trim logic.
- S:UScope, unchanged
- Impact is confined to erroneous discard/trim operations within the same privileged filesystem context on the affected host and shared storage; it does not cross VM, container, or IOMMU security boundaries.
- C:NConfidentiality impact, none
- The flaw causes incorrect discard of free clusters via sb_issue_discard and integer underflow in range arithmetic; it does not read kernel memory, leak pointers, or expose sensitive data to the attacker.
- I:HIntegrity impact, high
- Unsigned underflow can drive trimming far beyond the requested FITRIM range, issuing discard on extensive free-space regions on shared cluster storage and risking unintended loss or corruption of filesystem data integrity.
- A:HAvailability impact, high
- Corrupted len/last_group values can cause prolonged iteration through cluster groups while holding the exclusive OCFS2 cluster-wide trim DLM lock, enabling severe denial of service or hang for the node and other cluster members.