[CVE-2026-98522][MODERATE REGULAR] drm/imagination: Propagate map failures correctly from pvr_mmu_map_sgl()

[CVE-2026-98522][MODERATE REGULAR] drm/imagination: Propagate map failures correctly from pvr_mmu_map_sgl()

[AL-KERNEL]

CVE: CVE-2026-98522
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/imagination: Propagate map failures correctly from pvr_mmu_map_sgl()
Commit: 13c7ae1d92ceea18d55612fa9431ca5ac77025f5
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=13c7ae1d92ceea18d55612fa9431ca5ac77025f5
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98522
Analysis date: Mon, 19 Oct 2026 05:14:46 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
A local unprivileged PowerVR DRM client can encounter a kernel Oops when a successful cleanup operation hides an earlier GPU MMU mapping failure and allows processing to continue with invalid mapping state.

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

The original Linux kernel CVE announcement for CVE-2026-98522 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98522

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: NO

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

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

CVE-2026-98522	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98522 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE_KPANIC AEGIS_AS=1 LEGACY=MODERATE RESULT=DIFF (final Legacy and Aegis differ; FINAL: MODERATE, Aegis: MODERATE_KPANIC)	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-755;CWE-703;**CWE-476;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'A failure in pvr_mmu_map_sgl can be hidden because the original mapping error is overwritten by the result of the cleanup unmap operation. If cleanup succeeds, the function can incorrectly return success and pvr_mmu_map continues with incomplete or inconsistent GPU MMU state. Later processing can dereference a NULL or near NULL pointer and produce a kernel Oops, resulting in a local denial of service. For the CVSS the PR:L reflects that an unprivileged local process with access to the PowerVR DRM render device can reach the affected ioctl path without full administrative privileges. The base score uses AC:H because a GPU MMU mapping failure must occur before the incorrect success result is exposed. The paranoid score uses AC:L if crafted mapping requests or resource pressure can make that failure reliably repeatable. The issue is not network reachable. No UAF, OOB write, information disclosure, or arbitrary write primitive is demonstrated, so the supported impact is a kernel crash rather than privilege escalation. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 5.5 and the production ActionableScore returned 2 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. 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 V41_INHERITED_KPANIC_PROMOTION_BLOCKED and MANUAL_REVIEW_REQUIRED. The independent weaker Aegis shadow evaluated CVSS 2.4 and ActionableScore 1 with primitive class CLASS_C and manual review RECOMMENDED. Its independently reconciled impact was MODERATE_KPANIC. The models disagreed but the aggregation rules retained the production result. The final reported impact is MODERATE.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	MAYBE	OOB DANGER NULLPTR KERNEL_PANIC_PLUS_UAF HARDWARE LINUS IPV6  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH V41_INHERITED_KPANIC_PROMOTION_BLOCKED MANUAL_REVIEW_REQUIRED	-	-	checked

======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================

ActionableScore=2
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=NO
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

## 1. ActionableScore

* Raw conservative score: 2
* Conservative score: 2
* Raw paranoid score: 2
* Paranoid score: 2
* No floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::

## 2. Signal breakdown

Positive signals:

* +1 Local unprivileged trigger. The supplied trace shows UID 1000 reaching `pvr_ioctl_vm_map()` through the DRM ioctl path.
* +1 Reliable kernel crash or strong DoS. Incorrect success propagation causes continued MMU processing and a demonstrated NULL or near-NULL dereference at address `0x8`, producing a kernel Oops.

No additional points:

* The incorrect return value creates invalid operation state, but the demonstrated primitive remains a NULL dereference with no useful write or reuse mechanism.
* No UAF, heap OOB write, double release, stale refcount mutation, controlled reclaim, arbitrary write, disclosure, or authorization bypass is established.
* No additional availability point is awarded because it would duplicate the same Oops.
* NEW52 B5-R does not apply. There is no confirmed retry-accumulated heap OOB write or later consumption of corrupted heap state.
* V33 and V32 do not apply. No attacker-controlled active structured-state write or checksum metadata corruption exists.
* No hardware rarity penalty is applied merely because the defect is in a GPU driver.
* No timing penalty is applied. This is an ordered error-propagation failure, not a race.

## 3. Reachability analysis

The demonstrated actor is a local UID 1000 process executing `pvr_ioctl_vm_map()` through an accessible PowerVR DRM device. This positively supports below-host-admin reachability in the reported environment, so `HostAdminRequired=NO` and `RequiresHostUID0=NO`.

The complete trigger additionally requires an Imagination PowerVR device, the affected driver, access to its DRM node, and an initial MMU mapping failure. The evidence does not establish that every ordinary user on every affected deployment receives device access or can reliably force that mapping failure. No namespace capability is involved, no network trigger exists, and no race is required.

## 4. Primitive and severity interpretation

The root cause is loss of the original mapping error. On the error path, the vulnerable code assigns the return value of `pvr_mmu_op_context_unmap_curr_page()` to `err`. If cleanup succeeds, zero replaces the original failure, and `pvr_mmu_map_sgl()` incorrectly reports success.

The caller then consumes incomplete or inconsistent GPU MMU operation state. The demonstrated consequence is an invalid read through a NULL or near-NULL pointer and a kernel Oops. This is `CLASS_C`, not a lifetime violation or independently useful corruption primitive.

There is no concrete repeated release or refcount operation. No first operation frees an object, no dangling reference survives, and no second lifetime mutation occurs. The behavior therefore does not qualify for the repeated-lifetime exception or a UAF floor.

`ImportantCandidate=NO` because the evidence supports local DoS only. `AutoDowngradeAllowed=YES` because no unresolved write, lifetime, ownership, authorization, or cross-boundary primitive remains. Manual review is still recommended to confirm how reliably an unprivileged render-node client can induce the prerequisite mapping failure.

## 5. One-sentence report phrase

A local unprivileged PowerVR DRM client can encounter a kernel Oops when a successful cleanup operation hides an earlier GPU MMU mapping failure and allows processing to continue with invalid mapping state.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Verify whether an ordinary render-node client can reliably induce the initial `pvr_mmu_map_sgl()` failure in affected deployments. The supplied evidence does not support UAF, OOB write, privilege escalation, or an Important-preserving primitive.

## 7. Call-site confidence

Call-site confidence: high

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

Patch: drm/imagination: Propagate map failures correctly from pvr_mmu_map_sgl()
Commit: 13c7ae1d92ceea18d55612fa9431ca5ac77025f5
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=13c7ae1d92ceea18d55612fa9431ca5ac77025f5

Commit description:

Map failure from pvr_mmu_map_sgl() interface was not returned correctly
to pvr_mmu_map() interface. This resulted in pvr_mmu_map() interface to
continue instead of returning an error to caller.
Fix it by returning a proper error code from pvr_mmu_map_sgl() interface.

Call stack for crash:
[ 1179.286237] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
[ 1179.295067] Mem abort info:
[ 1179.297877]   ESR = 0x0000000096000004
[ 1179.301656]   EC = 0x25: DABT (current EL), IL = 32 bits
[ 1179.306987]   SET = 0, FnV = 0
[ 1179.310048]   EA = 0, S1PTW = 0
[ 1179.313198]   FSC = 0x04: level 0 translation fault
[ 1179.318096] Data abort info:
[ 1179.320993]   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
[ 1179.326483]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[ 1179.331546]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[ 1179.336895] user pgtable: 4k pages, 48-bit VAs, pgdp=000000009822a000
[ 1179.343402] [0000000000000008] pgd=0000000000000000, p4d=0000000000000000
[ 1179.350243] Internal error: Oops: 0000000096000004 [#2]  SMP
[ 1179.355908] Modules linked in: powervr gpu_sched drm_shmem_helper drm_gpuvm drm_exec xhci_plat_hcd xhci_hcd dwc3 usbcore usb_common snd_soc_simple_card snd_soc_simple_card_utils dwc3_am62 at24 sa2ul sha512 libsha512 sha256 authenc sch_fq_codel fuse dm_mod ipv6
[ 1179.378992] CPU: 1 UID: 1000 PID: 680 Comm: deqp-vk Tainted: G      D             6.17.0 #1 PREEMPT
[ 1179.388120] Tainted: [D]=DIE
[ 1179.390994] Hardware name: Texas Instruments AM625 SK (DT)
[ 1179.396467] pstate: 00000005 (nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 1179.403415] pc : pvr_mmu_op_context_unmap_curr_page+0x6c/0x134 [powervr]
[ 1179.410140] lr : pvr_mmu_op_context_unmap_curr_page+0x58/0x134 [powervr]
[ 1179.416848] sp : ffff8000839ab8c0
[ 1179.420153] x29: ffff8000839ab8c0 x28: 0000000000000001 x27: 000000008f386000
[ 1179.427283] x26: ffff000016d1df98 x25: 0000000000247000 x24: 00000000000001e6
[ 1179.434413] x23: 0000000000000002 x22: 000000000000ffff x21: 0000000000000247
[ 1179.441540] x20: 0000000000000245 x19: ffff000016d1df60 x18: 0000000000000002
[ 1179.448668] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000001
[ 1179.455793] x14: 0000000000060810 x13: ffff80007fffffff x12: ffff000004190480
[ 1179.462921] x11: ffff8000853f7000 x10: ffff8000811ae000 x9 : ffff0000041900b8
[ 1179.470051] x8 : 0000000000000000 x7 : 00000000990c4001 x6 : 0000000000000007
[ 1179.477177] x5 : ffff000016d1df60 x4 : 0000000000000000 x3 : ffff00000a7d8000
[ 1179.484306] x2 : 00000000000001ff x1 : 0000000000000000 x0 : 0000000000000000
[ 1179.491433] Call trace:
[ 1179.493872]  pvr_mmu_op_context_unmap_curr_page+0x6c/0x134 [powervr] (P)
[ 1179.500582]  pvr_mmu_map+0x31c/0x388 [powervr]
[ 1179.505027]  pvr_vm_gpuva_map+0x40/0x88 [powervr]
[ 1179.509732]  __drm_gpuvm_sm_map+0x250/0x44c [drm_gpuvm]
[ 1179.514952]  drm_gpuvm_sm_map+0x48/0x5c [drm_gpuvm]
[ 1179.519822]  pvr_vm_bind_op_exec+0x64/0x70 [powervr]
[ 1179.524785]  pvr_vm_map+0x1f8/0x2a8 [powervr]
[ 1179.529142]  pvr_ioctl_vm_map+0x12c/0x188 [powervr]
[ 1179.534018]  drm_ioctl_kernel+0xb8/0x128
[ 1179.537941]  drm_ioctl+0x21c/0x4ec
[ 1179.541337]  __arm64_sys_ioctl+0xac/0x108
[ 1179.545344]  invoke_syscall+0x44/0x100
[ 1179.549091]  el0_svc_common.constprop.0+0x40/0xe0
[ 1179.553790]  do_el0_svc+0x1c/0x28
[ 1179.557106]  el0_svc+0x34/0xf0
[ 1179.560159]  el0t_64_sync_handler+0xd0/0xe4
[ 1179.564334]  el0t_64_sync+0x198/0x19c
[ 1179.567996] Code: 54000300 35000360 f9402261 79409a62 (f9400421)
[ 1179.574081] ---[ end trace 0000000000000000 ]---

Fixes: ff5f643 ("drm/imagination: Add GEM and VM related code")
Reviewed-by: Alexandru Dadu <alexandru.dadu@imgtec.com>
Reviewed-by: Alessio Belle <alessio.belle@imgtec.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260922-mmu_fix-v4-1-12f1a871456a@imgtec.com
Signed-off-by: Brajesh Gupta <brajesh.gupta@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/imagination/pvr_mmu.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=13c7ae1d92ceea18d55612fa9431ca5ac77025f5

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

The original Linux kernel CVE announcement for CVE-2026-98522 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98522

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:L/UI:N/S:U/C:N/I:N/A:H
  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: unknown
  Paranoid ActionableScore: 2

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).