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CVE-2026-89801
drm/nouveau/uvmm: fix premature region free on failed OP_UNMAP_SPARSE
Published 2026-09-16 (33 days ago) by the Linux kernel CNA. Subsystem drivers/gpu. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-89801 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
In nouveau_uvmm_bind_job_submit()'s OP_UNMAP_SPARSE arm, op->reg is set from nouveau_uvma_region_find(), which only looks the region up and takes no reference; a region's sole reference is its membership in uvmm->region_mt. Two failure paths leave op->reg set: the -ENOENT check when the region is busy, and the drm_gpuvm_sm_unmap_ops_create() failure. The sibling nouveau_uvmm_sm_unmap_prepare() failure just below clears op->reg; these two do not. unwind_continue steps back one op, so the failing op is skipped by the unwind loop and its op->reg stays set. nouveau_uvmm_bind_job_cleanup() then enters its if (op->reg) branch and calls nouveau_uvma_region_remove() and nouveau_uvma_region_put() on it, dropping the tree's sole reference and freeing a region this job never created. The comment above the cleanup loop documents the broken invariant: op->reg must be NULL on submit failure. This frees a live region on an unrelated failure, reachable single-job when drm_gpuvm_sm_unmap_ops_create() returns -ENOMEM; if another job owns the same region, its cleanup then removes and puts the freed region, a use-after-free. Clear op->reg on both failure paths.
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/gpu/drm/nouveau/nouveau_uvmm.c
- What this is
- DRM DRIVER FOR NVIDIA GEFORCE/QUADRO GPUSMAINTAINERS section matched on drivers/gpu/drm/nouveau/ · dri-devel@lists.freedesktop.org · Supported
- Kernel module
- nouveau
Check it on the machine
grep -w CONFIG_DRM_NOUVEAU /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 nouveauPrints 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 1 release, so nothing is claimed about those.
- bookworm?
- trixieMnot built on amd64/cloud-amd64, arm64/cloud-arm64, armel/rpi, s390x/s390x
- forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64, s390x/s390x
- bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/cloud-arm64
- ?
- not established - no Makefile entry for the affected file
- M
- a module where it is built at all; some flavours do not build it
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_DRM_NOUVEAU
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
- 2026-09-16 (33 days 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
- 0.16%, higher than 4.6% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/gpu
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.6 | 6.6.157 | ba42d8a1c2c7 |
| 6.6 | 6.12.110 | 88114e3a9658 |
| 6.6 | 6.18.51 | 24c25b182d17 |
| 6.6 | 7.2.5 | 4083d24c2636 |
| 6.6 | 7.3 | ccf930812f23 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
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 through DRM_IOCTL_NOUVEAU_VM_BIND on a nouveau render node (/dev/dri/renderD*): nouveau_uvmm_ioctl_vm_bind → nouveau_job_submit → nouveau_uvmm_bind_job_submit. This is a local ioctl path, not a network, adjacent-radio, or physical-bus interface.
- AC:LAttack complexity, low
- An attacker can MAP_SPARSE a region, submit an async OP_UNMAP_SPARSE that dirties it while holding op->reg, then a second OP_UNMAP_SPARSE on the same range (or two unmaps in one ioctl). The failing path leaves op->reg set and cleanup frees the live region. The attacker drives both jobs, so no condition is outside their control.
- PR:LPrivileges required, low
- NOUVEAU_VM_INIT and NOUVEAU_VM_BIND are DRM_RENDER_ALLOW with no DRM_ROOT_ONLY or capability checks. Any unprivileged local user who can open the nouveau render node (typical render/video group) can trigger this without init-namespace root.
- UI:NUser interaction, none
- The attacker opens their own DRM client and issues VM_INIT/VM_BIND ioctls on that fd; no separate victim action such as mounting a filesystem or opening an attacker-controlled file is required.
- S:UScope, unchanged
- The use-after-free corrupts kernel heap state (struct nouveau_uvma_region) inside the host nouveau driver. Impact stays in the same kernel authority; this is not a VM escape or IOMMU/DMA isolation bypass.
- C:HConfidentiality impact, high
- Cleanup of a failed OP_UNMAP_SPARSE drops the maple-tree's sole reference and kfree()s a live nouveau_uvma_region another job still holds in op->reg. That use-after-free of a kernel object enables disclosure of reused slab contents, so confidentiality is High.
- I:HIntegrity impact, high
- The owning job's later cleanup calls sparse-unref, mas_erase, complete_all, and kref_put on the already-freed region. Heap spraying can reuse that object to corrupt kernel pointers and hijack control flow, so integrity is High.
- A:HAvailability impact, high
- Dereferencing the freed nouveau_uvma_region in nouveau_uvmm_bind_job_cleanup, maple-tree remove, or a later bind causes a kernel oops/panic; the attacker can repeat the sequence to crash or hang the system.