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CVE-2023-52590
ocfs2: Avoid touching renamed directory if parent does not change
Published 2024-03-06 (3 years 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-2023-52590 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 | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | fixed | 6.7.7-1 | Update the kernel and reboot. Fixed in 6.7.7-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 6.7.7-1 | Update the kernel and reboot. Fixed in 6.7.7-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 6.7.7-1 | Update the kernel and reboot. Fixed in 6.7.7-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The VFS will not be locking moved directory if its parent does not change. Change ocfs2 rename code to avoid touching renamed directory if its parent does not change as without locking that can corrupt the filesystem.
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/namei.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
- 2024-03-06 (3 years 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 5.9% 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 |
|---|---|---|
| 2.6.16 | 6.7.4 | de940cede3c4 |
| 2.6.16 | 6.8 | 9d618d19b29c |
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
- The vulnerable path is ocfs2_rename(), reached via the local rename/renameat syscalls through vfs_rename() on a mounted OCFS2 volume; OCFS2 is a shared-disk cluster filesystem, not a network protocol handler, so exploitation requires local access.
- AC:LAttack complexity, low
- The attacker controls both sides of the race—one thread issues same-parent directory renames while another creates/unlinks entries inside the renamed directory—so the missing VFS i_rwsem window can be hammered reliably without depending on external conditions.
- PR:LPrivileges required, low
- Only ordinary DAC write/rename permission on directories of an already-mounted OCFS2 volume is required; vfs_rename() enforces may_delete/may_create for the caller and there is no capability or init-namespace root check on this path.
- UI:NUser interaction, none
- In the realistic OCFS2 deployment the volume is already mounted for cluster shared storage; the attacker triggers the bug entirely with their own rename and directory-modification syscalls and needs no victim action.
- S:UScope, unchanged
- Corruption and any resulting remount-ro/panic stay inside the host kernel and the shared OCFS2 volume’s security authority; no VM escape, IOMMU bypass, or other cross-boundary impact occurs.
- C:HConfidentiality impact, high
- Racing the tautological ".." update against concurrent inline-directory expansion can tear directory contents so dirents carry wrong inode numbers, allowing lookups on the shared volume to open other users’/tenants’ files and disclose their data.
- I:HIntegrity impact, high
- The fix explicitly states that touching the unlocked renamed directory can corrupt the filesystem; torn directory blocks and inconsistent ".." / nlink metadata are durable on-disk integrity loss across the cluster volume, matching high-impact OCFS2 metadata corruption.
- A:HAvailability impact, high
- Corrupted directory metadata leads to ocfs2_check_dir_entry failures and ocfs2_error(), which remounts the filesystem read-only by default or panics under errors=panic, denying availability of the shared volume to all local and cluster users.