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CVE-2023-52591
reiserfs: Avoid touching renamed directory if parent does not change
Published 2024-03-06 (3 years ago) by the Linux kernel CNA. Subsystem fs/reiserfs. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2023-52591 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 reiserfs 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/reiserfs/namei.c
- What this is
- FILESYSTEMS (VFS and infrastructure)MAINTAINERS section matched on fs/* · linux-fsdevel@vger.kernel.org · Maintained
- Kernel module
- reiserfs
Check it on the machine
grep -w CONFIG_REISERFS_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 reiserfsPrints 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. The build rule could not be established for 2 releases, so nothing is claimed about those.
- bookworm, trixieMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- forky, sid?
- M
- a module where it is built at all; some flavours do not build it
- ?
- not established - no Makefile entry for the affected file
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switch
- CONFIG_REISERFS_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
- 0.24%, higher than 14.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- fs/reiserfs
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.12 | 6.6.16 | 17e1361cb91d |
| 2.6.12 | 6.7.4 | c04c162f82ac |
| 2.6.12 | 6.8 | 49db9b1b86a8 |
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 bug is reached only via local rename(2)/renameat2 on a mounted reiserfs volume (vfs_rename → reiserfs_rename); reiserfs is a block filesystem (FS_REQUIRES_DEV) with no in-protocol network entry point of its own.
- AC:LAttack complexity, low
- The attacker fully controls both sides of the race by concurrently renaming a subdirectory within the same parent and creating/unlinking entries inside it, so success does not depend on victim state or other attacker-uncontrollable conditions.
- PR:LPrivileges required, low
- Triggering requires only an unprivileged local user with write+exec on a parent directory on a mounted reiserfs filesystem (ordinary rename permission checks); CAP_SYS_ADMIN is not required once the volume is available, including via realistic desktop automount/udisks scenarios.
- UI:NUser interaction, none
- The attacker performs the concurrent rename and directory-modifying syscalls themselves on a filesystem they can access; no separate victim interaction is required at exploitation time.
- S:UScope, unchanged
- Impact is confined to the host kernel and the mounted reiserfs instance within the same OS security authority; there is no VM escape, IOMMU bypass, or other cross-boundary breakout.
- C:HConfidentiality impact, high
- Racing unlocked updates of directory/".." tree items can corrupt the global reiserfs B-tree such that subsequent lookups return the wrong objects or blocks, which is reasonably leveraged for disclosure of other users' file contents on the shared volume.
- I:HIntegrity impact, high
- The same unlocked rename path can journal stale or misplaced directory-item writes into the shared on-disk tree, corrupting filesystem metadata beyond the attacker's own entries and yielding unauthorized modification of volume-wide integrity.
- A:HAvailability impact, high
- Filesystem tree corruption can render the volume unusable and cause kernel oopses or hangs when later operations walk the damaged metadata, fully denying availability of the system or the mounted filesystem.