* [CVE-2026-98785][LOW] drm/amd/display: check dc_state_create_copy() for NULL in dm_suspend
@ 2026-10-24 11:43 21% AL-KERNEL
0 siblings, 0 replies; 1+ results
From: AL-KERNEL @ 2026-10-24 11:43 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98785
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/amd/display: check dc_state_create_copy() for NULL in dm_suspend
Commit: 686baa1f4ec43b33e39e3d4b4a4539a91d17e883
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=686baa1f4ec43b33e39e3d4b4a4539a91d17e883
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98785
Analysis date: Sat, 24 Oct 2026 07:43:17 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO
Summary:
An unchecked display-state copy allocation failure leaves a NULL cached state that is later dereferenced during GPU reset resume, causing a difficult-to-trigger kernel crash.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98785 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98785
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: LOW
Manual review required: NO
A detailed explanation of the methodology and priority rules is included
at the end of this message.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-98785 LOW https://www.kernelcve.org/list/?q=CVE-2026-98785 CHECK WITH IMPACT FROM ORIG NN LOW | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=LOW RESULT=DIFF TEMP_DISTANCE_MERGE_SKIP=AEGIS_NO_POSITIVE_SEVERITY_EVIDENCE (final Legacy and Aegis differ; FINAL: LOW, Aegis: MODERATE_KPANIC) Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';**CWE-476;CWE-252;CWE-703;BEST CVSS score: '4.7';DESCR 'An allocation failure in dc_state_create_copy() can leave cached_dc_state NULL because dm_suspend previously continued and returned success after the failed copy. dm_resume later passes this NULL state to link_enc_cfg_copy() and dereferences it while reading stream_count, causing a kernel crash during GPU reset recovery. For the CVSS the PR:L value reflects that a local process may influence GPU activity and memory pressure, although reliable triggering also requires a specific allocation failure during suspend or reset recovery. The demonstrated primitive is a NULL pointer dereference with availability impact only. There is no evidence of UAF, OOB access, information disclosure, or controlled memory corruption, and the issue is not directly network reachable. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 0 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage MODERATE_KPANIC to MODERATE because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE to LOW because the ActionableScore threshold rule was applied. final reconciliation stage LOW to LOW because the cross model evidence reconciliation rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH and DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 and V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED. The independent weaker Aegis shadow evaluated CVSS 4.7 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) MAYBE LOCK DANGER NOMEMCHK SIMPLEFIX DMAorINTERRUPT HARDWARE DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO
1. ActionableScore
* Raw base score: 0 (+1 crash, -1 difficult allocation-failure trigger).
* Conservative score: 0; no floor or cap applied.
* Raw paranoid score: 0; no technically supported additional primitive or reachability point.
* Paranoid score: 0.
* Final recommended bucket: **Ordinary Moderate**::
2. Signal breakdown
* +1 Reliable kernel crash: a failed `dc_state_create_copy()` leaves `cached_dc_state` NULL; successful suspend completion permits `dm_resume()` to dereference it.
* -1 Hard/unreliable trigger: exploitation requires allocation failure at the specific suspend/reset-recovery point. The supplied evidence only says a local process may influence GPU activity and memory pressure, not that it can reliably force this allocation failure.
* No UAF, OOB access/write, stale-object use, controlled corruption, disclosure, or authorization bypass is shown.
* No local-unprivileged bonus: access to GPU activity does not establish control of the complete suspend/allocation-failure/resume sequence.
* No extra availability point: it would duplicate the same NULL-dereference crash.
* NEW52/B5-R does not apply: there is no retry-accumulated index or heap OOB write.
* NEW53/B3-PENDING does not apply: no shared-backing write exists.
3. Reachability analysis
A local GPU-using process may contribute workload or memory pressure, but the actor able to initiate the relevant suspend/GPU-reset recovery sequence is not established. The complete trigger may involve DRM/display-management or system recovery privileges. Consequently, host-admin and namespace privilege requirements remain unknown. No network path, special hardware rarity penalty, or attacker-controlled race is established.
4. Primitive and severity reading
The exact primitive is a NULL pointer dereference caused by unchecked allocation failure and inconsistent cached-state initialization. It is neither active structured-state corruption nor a lifetime violation. The shown effect is kernel crash/availability loss during resume; non-crash exploit leverage is unsupported. This is CLASS_C, not an Important candidate, and ordinary downgrade is permitted.
5. One-sentence report phrase
An unchecked display-state copy allocation failure leaves a NULL cached state that is later dereferenced during GPU reset resume, causing a difficult-to-trigger kernel crash.
6. Manual review advice
NO MANUAL CHECK NEEDED
The patch and commit support only a constrained NULL-dereference availability defect.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: drm/amd/display: check dc_state_create_copy() for NULL in dm_suspend
Commit: 686baa1f4ec43b33e39e3d4b4a4539a91d17e883
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=686baa1f4ec43b33e39e3d4b4a4539a91d17e883
Commit description:
dc_state_create_copy() can return NULL on allocation failure.
dm_suspend() only conditionally skips dm_gpureset_toggle_interrupts()
and continues execution, returning success. dm_resume() then
dereferences the NULL cached_dc_state in link_enc_cfg_copy() and the
following dc_state->stream_count loop, crashing during GPU reset
recovery.
Return -ENOMEM immediately if the copy fails, so the caller aborts
suspend instead of leaving a NULL cached state for resume.
Fixes: 8092aa3 ("drm/amd/display: Add null checker before passing variables")
Reviewed-by: George Zhang <[email protected]>
Signed-off-by: Jiangshan Yi <[email protected]>
Tested-by: Dan Wheeler <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
(cherry picked from commit 84b6d79 )
Cc: [email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.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=686baa1f4ec43b33e39e3d4b4a4539a91d17e883
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98785 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98785
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: Not available
The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
The Best / paranoid CVSS score: 4.7
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: unknown
Paranoid ActionableScore: 0
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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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