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CVE-2026-72244
gpu/buddy: bail out of try_harder when alignment cannot be honoured
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem drivers/gpu. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-72244 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 | fixed | 6.12.101-1 | Update the kernel and reboot. Fixed in 6.12.101-1. 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. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4745-1 · 2026-08-18 · text | 6.12.101-1~deb12u1 | Update the kernel and reboot. DLA-4745-1 shipped the fix on 2026-08-18, in 6.12.101-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The try_harder contiguous fallback could return a range whose start offset did not match the caller's min_block_size. When a candidate's start is misaligned, realign it: free the misaligned run and reallocate exactly @size at the next lower min_block_size boundary. This keeps the returned size unchanged with no surplus to trim, and rejects the request only when no aligned candidate fits. v2: align misaligned candidates down to min_block_size instead of bailing out, for both the RHS and LHS paths (Matthew).
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/buddy.c
- What this is
- GPU BUDDY ALLOCATORMAINTAINERS section matched on drivers/gpu/buddy.c · dri-devel@lists.freedesktop.org · Maintained
Check it on the machine
grep -w CONFIG_GPU_BUDDY /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.
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?
- trixieYnot built on amd64/cloud-amd64, arm64/cloud-arm64, armel/rpi, s390x/s390x
- forky, sidYnot built on amd64/cloud-amd64, arm64/cloud-arm64, s390x/s390x
- bookworm · linux-6.12Ynot built on amd64/cloud-amd64, arm64/cloud-arm64
- ?
- not established - no Makefile entry for the affected file
- Y
- built in 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_GPU_BUDDY
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
- 7.8 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 5.2% 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 |
|---|---|---|
| 6.7 | 6.12.101 | 4289531106ee |
| 6.7 | 6.18.42 | 7185c5262435 |
| 6.7 | 7.1.5 | 419d7d930649 |
| 6.7 | 7.2 | 56bc6384314f |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4745-1 | 2026-08-18 | bookworm 6.12.101-1~deb12u1 | 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 in gpu_buddy_alloc_blocks() reached only via DRM GEM/TTM VRAM allocation ioctls (e.g. AMDGPU_GEM_CREATE, I915_GEM_CREATE, XE_GEM_CREATE) on /dev/dri/renderD*, requiring a local process with render-node access, not remote network input.
- AC:LAttack complexity, low
- An attacker can deterministically fragment VRAM with many GEM allocations and frees, then request GPU_BUDDY_CONTIGUOUS_ALLOCATION to force __alloc_contig_try_harder; no race or attacker-uncontrollable memory layout is required.
- PR:LPrivileges required, low
- Exploitation needs only standard unprivileged GPU client access to a DRM render node (render/video group membership), not real root or capabilities outside user namespaces; DRM_RENDER_ALLOW ioctls are available to normal desktop, container, and cloud GPU tenants.
- UI:NUser interaction, none
- No victim interaction is required; the attacker fully controls the allocation pattern and contiguous GEM creation requests needed to reach the vulnerable try_harder fallback path.
- S:UScope, unchanged
- Impact is cross-process GPU VRAM corruption or disclosure within the same kernel GPU memory authority (e.g. another user's buffers, page tables), not a VM escape, IOMMU/DMA boundary bypass, or other cross-authority scope change.
- C:HConfidentiality impact, high
- __alloc_contig_try_harder could return a misaligned or undersized contiguous range versus min_block_size; drivers trust this without post-check, so GPU page tables/DMA can read adjacent VRAM outside the intended buffer, enabling cross-allocation information disclosure.
- I:HIntegrity impact, high
- The same misaligned or short contiguous mapping lets GPU hardware write beyond the allocated VRAM window, corrupting neighboring buffers (including page tables) and providing an out-of-bounds write primitive in GPU memory space.
- A:HAvailability impact, high
- Incorrect contiguous VRAM placement can trigger GPU faults, AMDGPU/i915/XE recovery resets, display/compute hangs, and repeated driver-level failures when workloads use the corrupted mapping, causing high availability loss on affected systems.