[CVE-2026-63880][MODERATE REGULAR] drm/amdgpu: fix lock leak on ENOMEM in AMDGPU_GEM_OP_GET_MAPPING_INFO

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-63880
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/amdgpu: fix lock leak on ENOMEM in AMDGPU_GEM_OP_GET_MAPPING_INFO
Commit: 1eb86334e391695d4a40743b114afc15df4dc506
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1eb86334e391695d4a40743b114afc15df4dc506
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63880
Analysis date: Sun, 19 Jul 2026 19:37:10 -0400
ActionableScore: 4
ActionableScore lower bound: 3
Actionable bucket: Borderline, manual review recommended
Manual review required: YES

Summary:
A local unprivileged user with AMDGPU render node access can trigger an ENOMEM cleanup bug in AMDGPU_GEM_OP_GET_MAPPING_INFO, leaking a dma_resv lock and causing persistent GPU VM operations or process teardown to hang until reboot.

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ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-63880 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63880

The original announcement does not normally provide a security severity
estimate, CVSS assessment, or enough information to determine whether the
reported kernel bug represents a practically relevant security issue.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin. It combines
an autonomous classifier with LLM-assisted technical analysis and a
separate ActionableScore mechanism.

The purpose of this report is to prioritize Linux kernel CVEs before
manual review, identify cases that require prompt investigation, and
support automatic closure of issues that are unlikely to have meaningful
security impact.

Published priority for this report: MODERATE REGULAR
Manual review required: YES

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-63880	MODERATE	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';CWE-667;*CWE-772;**CWE-400;CWE-404;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'A lock leak in AMDGPU_GEM_OP_GET_MAPPING_INFO can occur when kvcalloc fails after amdgpu_gem_op_ioctl() has already acquired a GEM object reference and drm_exec related locks. The direct ENOMEM return skips the common cleanup path and can leave the per process VM root PD dma_resv lock held. A local process with access to /dev/dri/renderD* can trigger this through DRM_IOCTL_AMDGPU_GEM_OP because the ioctl is render node allowed. For the CVSS the PR:L is used because reliable triggering requires local code execution with access to the DRM render device, but it does not require full administrative privileges. The issue is not network reachable. Impact is denial of service against the affected GPU VM context and in the worst case an unkillable D state task that may persist until reboot. No memory corruption primitive is indicated, so confidentiality and integrity remain N in both scores.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 4)  SKIP CVE-2026-63880 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	NOMEMCHK LEAK ERRORPATH HARDWARE BOOT MEMORY  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=4
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 4
* Final recommended bucket: **Borderline, manual review recommended**::

## 2. Signal breakdown

Triggered signals:

* Local unprivileged trigger: +1
  DRM_IOCTL_AMDGPU_GEM_OP is DRM_RENDER_ALLOW, so a local user with access to /dev/dri/renderD* can reach the path without administrative privileges.

* Reliable strong DoS: +1
  The bug can leak a dma_resv lock and cause later operations on the same VM to block.

* Availability impact realistic: +1
  The reproduced behavior includes an unkillable D state task that may persist until reboot, which is stronger than a transient per-ioctl failure.

Paranoid-only signal:

* Broad/common deployed exposure: +1
  amdgpu render nodes are common on AMD GPU systems, especially desktop, workstation, and some APU deployments. This is still hardware-dependent, so I count it only in the paranoid score.

Not awarded:

* Generic memory corruption: +0
  The patch shows a cleanup path bug and lock/reference leak, not UAF, OOB write, double free, or type confusion.

* Privilege escalation plausible: +0
  No reclaim, overwrite, callback control, refcount takeover, or attacker-controlled object replacement is indicated.

* Confidentiality or integrity impact: +0
  The demonstrated impact is blocking on a leaked lock, not disclosure or modification of protected data.

## 3. Reachability analysis

A local process with access to an AMDGPU render node can trigger the ioctl path. This is commonly available to desktop users through /dev/dri/renderD* permissions, so PR is effectively local low privilege rather than root or CAP_SYS_ADMIN.

Namespaces and containers may matter if GPU render nodes are passed through to containers. In that case, a containerized or reduced-privilege workload with renderD access could affect its GPU context and possibly leave stuck host tasks tied to the device file lifecycle.

The path is not network reachable. Triggering depends on AMDGPU hardware, the affected kernel, and inducing the kvcalloc ENOMEM branch in AMDGPU_GEM_OP_GET_MAPPING_INFO.

## 4. Severity interpretation

This behaves like a stronger local DoS rather than an Important memory-corruption vulnerability. The practical evidence supports persistent availability impact, including a D state task until reboot. However, the patch does not support confidentiality impact, integrity impact, arbitrary memory corruption, or privilege escalation.

The conservative result is borderline Moderate. The paranoid result remains below Actionable Moderate because the vulnerability class is a lock/resource leak, not a corruption primitive.

## 5. One-sentence report phrase

A local unprivileged user with AMDGPU render node access can trigger an ENOMEM cleanup bug in AMDGPU_GEM_OP_GET_MAPPING_INFO, leaking a dma_resv lock and causing persistent GPU VM operations or process teardown to hang until reboot.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Manual review is recommended because the bug is reachable through an unprivileged render node and has reproduced persistent D state behavior, but it does not show memory corruption or privilege escalation evidence.

======================================================================
UPSTREAM PATCH SUMMARY
======================================================================

Patch: drm/amdgpu: fix lock leak on ENOMEM in AMDGPU_GEM_OP_GET_MAPPING_INFO
Commit: 1eb86334e391695d4a40743b114afc15df4dc506
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1eb86334e391695d4a40743b114afc15df4dc506

Commit description:

The AMDGPU_GEM_OP_GET_MAPPING_INFO branch of amdgpu_gem_op_ioctl()
holds three cleanup-tracked resources before calling kvcalloc():
the drm_gem_object reference from drm_gem_object_lookup(), the
drm_exec lock on the looked-up GEM via drm_exec_lock_obj(), and
the drm_exec lock on the per-process VM root page directory via
amdgpu_vm_lock_pd().  All three are released by the out_exec
label that every other error path in this function jumps to.
The kvcalloc() failure path returns -ENOMEM directly, skipping
out_exec and leaking all three.

The leaked per-process VM root PD dma_resv lock is the
load-bearing leak: any subsequent operation on the same VM
(further GEM ops, command-submission, eviction, TTM shrinker
callbacks) blocks on the held lock.  DRM_IOCTL_AMDGPU_GEM_OP is
DRM_AUTH | DRM_RENDER_ALLOW, so this is an unprivileged-local
denial of service against the caller's GPU context, reachable
by any process with /dev/dri/renderD* access.

Route the failure through out_exec so drm_exec_fini() and
drm_gem_object_put() run.

Reproduced on stock 7.0.0-10, Ryzen 7 5700U / Radeon Vega
(Lucienne): the failing ioctl returns -ENOMEM and a second
GET_MAPPING_INFO on the same fd then blocks in
drm_exec_lock_obj() on the leaked dma_resv.  SIGKILL on the
caller does not reap the task; the fd-release path during
process exit goes through amdgpu_gem_object_close() ->
drm_exec_prepare_obj() on the same lock, leaving the task in D
state until the box is rebooted.  The patched kernel was not
rebuilt and re-tested on this hardware; the fix is mechanical.
Tested on a single Lucienne / Vega box only.

Ziyi Guo posted an independent INT_MAX-bound check for
args->num_entries in the same branch [1]; the two patches are
complementary and can land in either order.

Fixes: 4d82724 ("drm/amdgpu: Add mapping info option for GEM_OP ioctl")
Link: https://lore.kernel.org/all/20260208000255.4073363-1-n7l8m4@u.northwestern.edu/ # [1]
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit b69d325 )
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c

Diff excerpt:

Not included in this email. See the upstream URL for the full patch.

Full patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1eb86334e391695d4a40743b114afc15df4dc506

======================================================================
DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2026-63880 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-63880

The original CVE announcement normally does not include a security-level
estimate. In particular, it may not contain a CVSS assessment, an impact
level, or enough information to determine whether the reported bug is a
practically relevant security issue. One purpose of this parallel CVE list
is to provide that missing technical and prioritization information.

The original goal of the AL-KERNEL project was to prioritize Linux kernel
CVE analysis automatically before manual review. The system can also help
identify non-security issues that may be suitable for automatic closure.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin.

The first analysis stage combines an autonomous classifier with additional
LLM-based analysis. The autonomous classifier runs locally on a CPU and is
based on a backpropagation neural network. Together, these mechanisms
produce a technical vulnerability description, identify likely weakness
types, estimate CVSS severity, and provide input for ActionableScore.

Two CVSS estimates are retained because incomplete kernel vulnerability
information often permits more than one defensible interpretation:

  Conservative CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.5

The conservative vector represents a lower-impact interpretation.
The Best/paranoid vector intentionally represents a plausible upper-bound
interpretation and should not automatically be treated as demonstrated
real-world impact.

CVSS may also need to be adjusted for a particular Linux deployment,
because actual reachability, privileges, enabled kernel configuration,
hardware, namespaces, exposed device nodes, and other environmental
conditions can differ significantly between systems.

A separate ActionableScore mechanism evaluates practical remediation
urgency. Its analysis may include reachability, attack prerequisites,
subsystem exposure, memory-corruption characteristics, denial-of-service
reliability, and possible confidentiality, integrity, or
privilege-escalation impact.

  Conservative ActionableScore: 3
  Paranoid ActionableScore: 4

The final base severity is taken directly from the second tab-separated
field of the AL-KERNEL classification result. ActionableScore does not
replace or independently override that final AL-KERNEL decision, and
if ActionableScore adjusted impact level of ALKERNEL, then you would see
self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7.

For an AL-KERNEL result of MODERATE, this report uses the following
additional presentation split:

  ActionableScore below 5   -> MODERATE REGULAR
  ActionableScore 5 or more -> MODERATE 7.0

The distinction between MODERATE REGULAR and MODERATE 7.0 makes it
possible to identify Moderate issues that should receive manual analysis
and fixes before lower-priority MODERATE REGULAR issues. In many cases,
MODERATE REGULAR fixes may wait for a later rebase or routine update.

There is one override in which MODERATE REGULAR becomes MODERATE 7.0
even when the ActionableScore is below 5. When the AL-KERNEL result
contains the KPANIC flag, a MODERATE result is always presented as
MODERATE 7.0. The KPANIC flag selected with few regexps without
usage of AI at all, so it helps to detect cases when Kernel Crash happens
and similar (to filter False-Negative results from the LLM usage).

KPANIC indicates that a reliable kernel crash, kernel panic, or similarly
serious kernel availability impact was identified by the classification
workflow.

AL-KERNEL base severity for this report: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

These results are intended to support engineering triage. They are
machine-generated estimates, and cases marked for manual review should
be validated by a human security engineer before final disposition.
For more info read docs linked from here: https://kernelcve.org/
(and you can submit you own patch there to generate such a report
for non-existant CVE-id yet).

Note that in many cases this AI tool selects higher severity, than
real is (means you can expect Importants instead of Moderate 7.0 or
Moderates 7.0 instead of regular Moderates). If you see such cases,
please use reply email interface to add additional manual analyses
info to this particular CVE.
And please, please, let me know when you see Lows instead of Importants
or Important instead of Low (because particular for such cases I
need to tune this AI tool to make it better for this one and next similar).
My contact email for such notifications is alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).