* [CVE-2026-89877][MODERATE 7.0] media: saa7164: fix cleanup on resource allocation failure
@ 2026-09-16 11:27 21% AL-KERNEL
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From: AL-KERNEL @ 2026-09-16 11:27 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-89877
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: media: saa7164: fix cleanup on resource allocation failure
Commit: daa5b32cdf7db81a07ee2a91ce092a363e7754aa
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=daa5b32cdf7db81a07ee2a91ce092a363e7754aa
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89877
Analysis date: Wed, 16 Sep 2026 07:27:47 -0400
ActionableScore: 5
ActionableScore lower bound: 4
Actionable bucket: Actionable Moderate / Strong Important candidate requiring manual review
Manual review required: YES
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-89877 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89877
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 7.0
Manual review required: YES
A detailed explanation of the methodology and priority rules is included
at the end of this message.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-89877 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-89877 CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';*CWE-416;*CWE-672;*CWE-772;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.8';DESCR 'saa7164_dev_setup can leave a freed device object linked on the global saa7164_devlist when PCI BAR resource allocation fails during probe. Later list traversal or driver recovery paths may access this dangling list entry, creating a use after free candidate and likely kernel crash. For the CVSS the PR:L is used in the paranoid score because a reduced capability local administrator or service with driver bind, module reload, or PCI rescan control may be able to trigger the failed probe path. The issue is not network reachable and requires local control over driver or PCI device lifecycle rather than packet traffic. Impact is at least local denial of service. In the worst still defensible case it may allow limited confidentiality or integrity impact due to reuse of a freed kernel object, so it should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate / Strong Important candidate requiring manual review (with actual score 5) YES SIMPLEFIX ERRORPATH HARDWARE LINUS KPANIC INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK NO NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=5
ActionableScoreLower=4
PrimitiveClass=CLASS_B
RealUAF=YES
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=YES
ManualReview=REQUIRED
AutoDowngradeAllowed=NO
1. ActionableScore
* Raw conservative score: 4
* Conservative score: 4. No floor or cap applied.
* Raw paranoid score: 5
* Paranoid score: 5. No floor or cap applied.
* Final recommended bucket: **Actionable Moderate / Strong Important candidate requiring manual review**::
2. Signal breakdown
Conservative signals:
* +2 Real UAF / lifetime violation. The device is added to the global `saa7164_devlist`, `get_resources()` may fail, the probe error path later frees the device, and the old global-list entry can remain dangling.
* +1 Reliable kernel crash / strong DoS. Later traversal or use of the global list can dereference the freed `saa7164_dev` object and plausibly cause an Oops or crash.
* +1 Concrete persistent kernel resource leak. If BAR0 is requested successfully and BAR2 fails, BAR0 was not released before the fix.
* +0 Privilege uncertainty. Triggering the failed PCI probe path likely requires device lifecycle control, driver bind or resource-conflict conditions, but the supplied evidence does not fully prove host-admin-equivalent privilege as the only possible attacker model.
Paranoid additional signal:
* +1 Escaping active structured stale object. The freed `saa7164_dev` is not merely used once in a local cleanup helper. It can remain discoverable through a global kernel list, so later kernel paths may treat reclaimed memory as an active driver object. Controlled reclaim is not demonstrated, so this remains Class B, not Class A.
Important non-awarded signals:
* Controlled reclaim is not demonstrated.
* Arbitrary read or arbitrary write is not demonstrated.
* Callback or function pointer control is not demonstrated.
* Remote reachability is not established.
* Local unprivileged reachability is not established.
* Confidentiality and integrity impact are not awarded as separate positive signals because no disclosure path, controlled write, or privilege escalation primitive is shown.
* Extra Availability is not awarded because the plausible crash is already counted once.
* Concrete repeated release/refcount signal is not awarded. The first lifetime end is the probe error path freeing the device, and the exact reference survives in the list, but the supplied patch does not show a concrete second `put`, `release`, `free`, or refcount mutation on the same dangling reference.
* FLOOR 5 for repeated release/refcount is not applied because no concrete second lifetime-mutating operation is shown.
3. Reachability analysis
The vulnerable path is in PCI media driver probe/setup for the SAA7164 device. The trigger requires `saa7164_dev_setup()` to publish the device on the global list and then fail during PCI BAR resource acquisition.
A normal local user is not shown to be able to directly force this path. Likely practical triggers involve host-controlled driver loading, binding, unbinding, PCI rescan, hotplug, resource conflicts, or faulty hardware behavior. These are commonly administrative or device-management operations, but the supplied evidence does not fully resolve the complete privilege boundary, so `HostAdminRequired=UNKNOWN` is used rather than assuming either host admin or ordinary user reachability.
This is not namespace-scoped. No network namespace, user namespace, or container-scoped capability path is involved. There is no direct network trigger.
Special hardware is involved because the driver is for SAA7164 PCI media hardware, but no separate hardware penalty is applied in the score because the key triage question is the kernel lifetime primitive once the driver path is reached.
No race is required. This is an ordered error-path cleanup bug rather than a timing-window race.
4. Primitive and severity interpretation
The exact primitive is a stale global-list entry pointing to a freed `struct saa7164_dev`. This is a real lifetime violation and UAF candidate. The stale object is an active structured driver object, not fixed stale DMA storage.
The demonstrated consequence is likely local kernel crash or DoS if a later list traversal or driver path consumes the dangling entry. The speculative consequence is limited post-free object confusion if the freed memory is reused before a later traversal, but the patch does not establish controlled replacement, attacker-shaped reclaimed contents, arbitrary read/write, or privilege escalation.
This is `PrimitiveClass=CLASS_B`: a real kernel lifetime primitive exists, but strong exploitation leverage is not directly established.
`ImportantCandidate=YES` because the freed object escapes through a global list and later active structured use is unresolved. This is stronger than a purely local cleanup-only stale dereference.
`AutoDowngradeAllowed=NO` because automatically closing this as ordinary crash-only Moderate would discard a concrete dangling global-list UAF primitive whose later use is not fully characterized.
Likely operational severity is Actionable Moderate. It is not independently proven Important, but it requires manual review before downgrade.
5. One-sentence report phrase
A failed SAA7164 PCI BAR allocation can leave a freed device object linked on the global driver list, creating a dangling structured kernel object that may later be dereferenced and cause a local kernel crash or unresolved UAF behavior.
6. Manual review recommendation
MANUAL CHECK REQUIRED
The issue contains a real UAF candidate with a freed active driver object escaping through a global list. Controlled exploitation is not shown, but the post-lifetime use surface is not sufficiently constrained for safe automatic downgrade.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: media: saa7164: fix cleanup on resource allocation failure
Commit: daa5b32cdf7db81a07ee2a91ce092a363e7754aa
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=daa5b32cdf7db81a07ee2a91ce092a363e7754aa
Commit description:
saa7164_dev_setup() adds the device to the global saa7164_devlist before
requesting the PCI BAR memory regions.
If get_resources() fails, saa7164_dev_setup() decrements the device count
and returns an error, but leaves the device on saa7164_devlist. The probe
error path then frees the device, leaving a dangling entry on the global
list.
Reuse the existing MMIO mapping error path to remove the device from
saa7164_devlist and decrement the device count before returning.
Also release BAR0 if it was successfully requested but the BAR2 request
fails.
Fixes: 443c122 ("V4L/DVB (12923): SAA7164: Add support for the NXP SAA7164 silicon")
Cc: [email protected]
Signed-off-by: Guangshuo Li <[email protected]>
Signed-off-by: Hans Verkuil <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
drivers/media/pci/saa7164/saa7164-core.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=daa5b32cdf7db81a07ee2a91ce092a363e7754aa
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-89877 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89877
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:L/I:L/A:H
The Best / paranoid CVSS score: 5.8
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: 4
Paranoid ActionableScore: 5
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: YES
Published priority for this report (same as in Subject): MODERATE 7.0
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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