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CVE-2026-93175
drm/amd/display: Fix dangling pointer in CRTC reset function
Published 2026-09-17 (31 days ago) by the Linux kernel CNA. Subsystem drivers/gpu. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-93175 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 | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| 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. |
The vulnerability
What the bug is
amdgpu_dm_crtc_reset_state() frees the old state before allocating a new one. If kzalloc() fails, the function returns without updating the state pointer, leaving a dangling pointer to already freed memory. Fix this by allocating the new state first. On allocation failure, the old state remains untouched and the function safely returns. Found by Linux Verification Center (linuxtesting.org) with SVACE. [adjust for movement around current amd-staging-drm-next]
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/amd/display/amdgpu_dm/amdgpu_dm_crtc.c
- What this is
- AMD DISPLAY COREMAINTAINERS section matched on drivers/gpu/drm/amd/display/ · amd-gfx@lists.freedesktop.org · Supported
Show whether Debian builds this, per release
Not established. This site could not find the build rule for the affected file in the kernel trees Debian ships, so it has no answer about whether Debian compiles this code. Read that as unknown, never as absent.
- bookworm, trixie, forky, sid?
- ?
- 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.
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
Signals
- Published
- 2026-09-17 (31 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
- 0.17%, higher than 6.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- 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 |
|---|---|---|
| 4.15 | 6.18.57 | 3a03827bb3cd |
| 4.15 | 7.2.6 | 32bd68edbc6c |
| 4.15 | 7.3 | 0aeed866cb93 |
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 dangling crtc->state is created in amdgpu_dm_crtc_reset_state(), which drm_mode_config_reset() invokes from drm_atomic_helper_resume() in dm_destroy_cached_state(). That runs from dm_resume() on S3 (amdgpu_pmops_resume -> amdgpu_device_resume) and on runtime resume when drm_open/amdgpu_driver_open_kms or amdgpu_drm_ioctl call pm_runtime_get_sync(). No protocol message carries the trigger.
- AC:LAttack complexity, low
- After a successful amdgpu_dm_crtc_init() reset, crtc->state is live. The buggy amdgpu_dm_crtc_reset_state() then always kfree's it via amdgpu_dm_crtc_destroy_state() before kzalloc_obj(*state); on GFP_KERNEL ENOMEM it returns without clearing crtc->state. A local attacker can force that allocation failure with memory pressure; there is no race.
- PR:LPrivileges required, low
- amdgpu_driver_open_kms() has no capable() check and always calls pm_runtime_get_sync(); amdgpu_drm_ioctl() does the same before drm_ioctl(). Access is the usual /dev/dri/cardN and renderD* nodes granted to the seat user by logind ACLs or the video/render group, not init-namespace root.
- UI:NUser interaction, none
- The attacker opens /dev/dri/renderD* or issues an amdgpu ioctl after amdgpu autosuspend (pm_runtime_put_autosuspend, 5s delay on the default BACO/PX/BOCO path when no CRTC is active); dm_resume() then runs drm_mode_config_reset() without another user mounting media or plugging hardware.
- S:UScope, unchanged
- The use-after-free is of host-kernel dm_crtc_state on the amdgpu display CRTC. It does not escape a KVM/Xen guest, bypass the IOMMU, or leave a sandbox.
- C:HConfidentiality impact, high
- amdgpu_dm_crtc_destroy_state() kfree's the live dm_crtc_state while crtc->state still points at it. drm_atomic_helper_commit_duplicated_state() then loads that freed object as old_state, including dc_stream_state *stream and drm_crtc_state mode_blob/commit/event pointers, a slab UAF read.
- I:HIntegrity impact, high
- The same dangling crtc->state is installed as old_state and later passed to atomic_destroy_state again (double-free). Heap reuse of dm_crtc_state lets an attacker control stream, commit, and event pointers consumed by the resume atomic commit, a write and control-flow primitive.
- A:HAvailability impact, high
- drm_atomic_helper_commit_duplicated_state() immediately dereferences the freed dm_crtc_state after drm_mode_config_reset(), causing a kernel oops; the later second destroy is a double-free. Either path oopses or panics the host.