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CVE-2025-37977
scsi: ufs: exynos: Disable iocc if dma-coherent property isn't set
Published 2025-05-20 (17 months ago) by the Linux kernel CNA. Subsystem drivers/ufs. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2025-37977 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 | 6.12.27-1 | Update the kernel and reboot. Fixed in 6.12.27-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 6.12.27-1 | Update the kernel and reboot. Fixed in 6.12.27-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 6.12.27-1 | Update the kernel and reboot. Fixed in 6.12.27-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
If dma-coherent property isn't set then descriptors are non-cacheable and the iocc shareability bits should be disabled. Without this UFS can end up in an incompatible configuration and suffer from random cache related stability issues.
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.
drivers/ufs/host/ufs-exynos.c
drivers/ufs/host/ufs-exynos.h
- What this is
- UNIVERSAL FLASH STORAGE HOST CONTROLLER DRIVER EXYNOS HOOKSMAINTAINERS section matched on drivers/ufs/host/ufs-exynos* · linux-scsi@vger.kernel.org · Maintained
- Kernel module
- ufs_exynos
Check it on the machine
grep -wE 'CONFIG_SCSI_UFSHCD|CONFIG_SCSI_UFS_EXYNOS' /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 ufs_exynosPrints 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 does not build this code in 1 release. It does build it in 3 releases, so the answer depends on which release the machine runs.
- bookwormn
- trixieMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- forky, sidMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt-amd64, arm64/cloud-arm64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- n
- not enabled on any flavour - this release does not build the code
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_SCSI_UFSHCD, CONFIG_SCSI_UFS_EXYNOS
- Reads as
- all on means the file is compiled; any one off means it is not.
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
- 2025-05-20 (17 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
- 0.20%, higher than 8.8% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/ufs
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.16 | 6.12.26 | 869749e48115 |
| 5.16 | 6.14.4 | f0c6728a6f2e |
| 5.16 | 6.15 | f92bb7436802 |
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 code is an Exynos UFS host controller driver path programmed at probe time and exercised by ordinary block/filesystem I/O to the local storage device. There is no network-facing consumer, so reaching it requires local access to issue I/O.
- AC:LAttack complexity, low
- The coherency configuration is systematically wrong on every transfer on affected platforms — not a narrow race the attacker must win — and a local process can reliably drive sustained UFS I/O plus cache pressure to surface the incoherency. No precondition lies outside the attacker's influence.
- PR:LPrivileges required, low
- Any unprivileged local process can generate the UFS traffic that flows through the mismatched descriptor rings and streaming DMA mappings via normal file reads and writes. No capability or root access is needed.
- UI:NUser interaction, none
- The broken shareability programming is applied at driver probe and takes effect on all subsequent I/O; no victim action such as mounting a filesystem or opening a crafted file is required.
- S:UScope, unchanged
- The incoherent DMA is confined to buffers the kernel itself mapped for the UFS controller, so the impact stays within the kernel/OS security authority. It is a cache shareability attribute mismatch, not an IOMMU or DMA-boundary bypass.
- C:HConfidentiality impact, high
- With DMA_FROM_DEVICE the post-transfer invalidate can discard the device-written line, leaving the CPU to read the physical page's prior contents — previously freed kernel or other-process memory — and return it to userspace as file data. The driver likewise consumes stale device-written response UPIU and sense data from non-cacheable descriptor memory.
- I:HIntegrity impact, high
- Device writes can be dropped and stale cache contents flushed to the storage device, corrupting file data and filesystem metadata on the primary boot medium, and the driver acts on stale descriptor/status fields it believes the controller wrote.
- A:HAvailability impact, high
- The commit explicitly cites random cache-related stability issues; incoherent UTRD/UTMRD rings lead to misparsed completions, I/O timeouts, controller resets, hangs and kernel crashes on the root storage device.