* [CVE-2026-98270][LOW] drm/amdgpu: check ras and obj before dereference [ Upstream
@ 2026-10-10 20:38 21% AL-KERNEL
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From: AL-KERNEL @ 2026-10-10 20:38 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-98270
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: drm/amdgpu: check ras and obj before dereference [ Upstream
Commit: b7c7f07a40037514f8e890aa00f8d7b196d680cf
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b7c7f07a40037514f8e890aa00f8d7b196d680cf
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98270
Analysis date: Sat, 10 Oct 2026 16:38:01 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98270 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98270
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-2026-98270 LOW https://www.kernelcve.org/list/?q=CVE-2026-98270 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 (independent 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-362;CWE-754;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'The AMDGPU NBIO v7.9 RAS interrupt handler can dereference a NULL RAS context or PCIE_BIF RAS object during the initialization window before the object is created. An interrupt in this window executes the faulty access in hard IRQ context and can cause a kernel Oops or panic, resulting in a local denial of service. For the CVSS the PR:L value is used for the paranoid score because a local process with access to the GPU render interface may be able to influence GPU activity without full administrative privileges, although reliable control of a fatal RAS interrupt is not established. AC:H applies because successful triggering depends on an interrupt arriving during a narrow initialization window. The issue is not network reachable. The demonstrated primitive is a NULL pointer read rather than UAF, OOB access, or arbitrary write, so the supported impact is availability loss without confidentiality or integrity impact.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0) MAYBE KASAN WARNONLY SIMPLEFIX HARDWARE - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO
1. ActionableScore
* Raw conservative score: 0
* Conservative score: 0
* Raw paranoid score: 0
* Paranoid score: 0
* No floor or cap was applied.
* Final recommended bucket: **Ordinary Moderate**::
2. Signal breakdown
* +1 Reliable kernel crash. Dereferencing a NULL `ras` or `obj` pointer in hard-IRQ context can produce a kernel Oops or panic.
* -1 Hard and externally uncontrolled timing. A RAS interrupt must arrive during the initialization window after `adev->nbio.ras` is exposed but before the `PCIE_BIF` RAS object is created.
* +0 Weak corruption concern. The established primitive is an invalid NULL-pointer read, not a useful memory-corruption primitive.
* No additional availability point was awarded because it would duplicate the same kernel crash.
* No local-unprivileged bonus was awarded. Access to a render node does not establish control over a fatal RAS interrupt or the complete initialization sequence.
* No firmware-mediated or remote-reachability bonus was awarded.
* No UAF, OOB access, arbitrary write, controlled reclaim, disclosure, authorization bypass, or privilege escalation is established.
* B5-R does not apply because there is no heap OOB write, retry-accumulated index, or later consumption of corrupted descriptor state.
* B3-PENDING does not apply because no shared-backing write occurs.
* B4-PENDING does not apply because no authorization decision or mandatory security guard is involved.
* No concrete repeated release or refcount operation exists. FLOOR 5 is therefore inapplicable.
3. Reachability analysis
The vulnerable operation runs in the AMDGPU NBIO v7.9 RAS fatal-error interrupt handler during device initialization. The supplied evidence does not establish that an ordinary logged-in user, render-node client, compositor, DRM master, delegated graphics service, or host administrator can deliberately generate the required RAS interrupt during the vulnerable window.
The interrupt and initialization state concern a physical GPU and are not namespace-scoped. No network path exists. Prior hardware and driver initialization are prerequisites, but common AMD GPU hardware is not treated as rare hardware. The complete attacker privilege requirement remains unresolved, so `HostAdminRequired=UNKNOWN` rather than assuming either host administration or below-host-admin reachability.
The timing condition is materially narrow and externally uncontrolled on the supplied evidence. Repeated device reset or fault-injection control might alter reachability, but neither is established here.
4. Primitive and severity interpretation
The exact primitive is a NULL-pointer dereference through `ras` or `obj` in hard-IRQ context. This is neither stale storage nor an active structured-object UAF. There is no release, lifetime transition, post-free access, repeated refcount mutation, or corrupted-state consumption.
The demonstrated consequence is a kernel crash. A reliable attacker-controlled trigger is not demonstrated. Stronger consequences such as memory corruption, information disclosure, privilege escalation, or attacker-directed GPU or host-state modification are speculative and unsupported.
`PrimitiveClass=CLASS_C` is appropriate because the behavior is an invalid-state dereference with crash/DoS impact and no independently useful corruption primitive. `ImportantCandidate=NO` and `AutoDowngradeAllowed=YES` follow because no Important-preserving B5-R, B3-PENDING, B4-PENDING, lifetime, ownership, or authorization primitive exists.
Operationally, this is an ordinary Moderate or Low-like reliability issue unless further hardware-specific evidence shows that a below-host-admin actor can reliably force the fatal RAS interrupt during repeated initialization or reset cycles.
5. One-sentence report phrase
A NULL dereference in the AMDGPU NBIO v7.9 RAS interrupt handler can crash the kernel if a fatal error interrupt arrives during a narrow initialization window, but attacker control of that interrupt and timing is not established.
6. Manual review recommendation
MANUAL CHECK RECOMMENDED
Confirm whether supported AMDGPU fault-injection, reset, virtualization, or render-node operations allow a below-host-admin actor to repeatedly generate the relevant RAS interrupt during initialization. This review concerns trigger reachability only and does not change the established crash-only primitive.
7. Call-site confidence
Call-site confidence: high
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: drm/amdgpu: check ras and obj before dereference [ Upstream
Commit: b7c7f07a40037514f8e890aa00f8d7b196d680cf
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b7c7f07a40037514f8e890aa00f8d7b196d680cf
Changed files:
drivers/gpu/drm/amd/amdgpu/nbio_v7_9.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=b7c7f07a40037514f8e890aa00f8d7b196d680cf
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-98270 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98270
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:H/PR:H/UI:N/S:U/C:N/I:N/A:H
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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