[CVE-2026-72097][LOW] dm-verity: fix a possible NULL pointer dereference commit e72b793ae440f6900fb17a4b8518c707b5cd3e17 upstream.

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

CVE: CVE-2026-72097
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: dm-verity: fix a possible NULL pointer dereference commit e72b793ae440f6900fb17a4b8518c707b5cd3e17 upstream.
Commit: 7d4f1d307ac0f4f55cebeb192a90a235aa060ed1
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7d4f1d307ac0f4f55cebeb192a90a235aa060ed1
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72097
Analysis date: Sun, 16 Aug 2026 00:26:04 -0400
ActionableScore: 2
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like. Not an Actionable Moderate
Manual review required: NO

Summary:
A missing NULL check in the dm-verity LoadPin helper can let a local privileged or delegated device-mapper actor trigger a kernel NULL-pointer dereference when a DM device has no live table, causing denial of service only.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-72097 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72097

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.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-72097	LOW	CHECK WITH IMPACT FROM ORIG NN MODERATE	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-476;CWE-252;CWE-703;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.5';DESCR 'dm-verity LoadPin helper can dereference a NULL live device mapper table when checking whether a block device is trusted. A local attacker or local process that can cause dm_verity_loadpin_is_bdev_trusted to run on a DM device with no active table may trigger a kernel crash. For the CVSS the PR:L is used for the paranoid score because some deployments may delegate device mapper control to a reduced capability local administrator or service account, while the normal reliable trigger usually requires CAP_SYS_ADMIN. The issue is not network reachable and there is no evidence of a UAF, out of bounds write, information leak, or privilege escalation primitive. Impact is denial of service via NULL-pointer dereference only.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like. Not an Actionable Moderate (with actual score 1)  SKIP CVE-2026-72097 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	NULLPTR DISK SIMPLEFIX HARDWARE LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=2
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like. Not an Actionable Moderate**::

## 2. Signal breakdown

Conservative signals:

* Reliable kernel crash / strong DoS: +1. The patch fixes a direct NULL pointer dereference of `table->num_targets` when `dm_get_live_table()` returns NULL.
* Important filesystem/storage path: +1. The affected code is in dm-verity LoadPin integration, which is storage and trust-policy adjacent.
* Requires admin/root/CAP_SYS_ADMIN in typical deployments: -2. Creating or manipulating device-mapper devices and table state normally requires administrative privileges.

Paranoid adjustment:

* The paranoid score removes the full privilege penalty and treats delegated device-mapper control by a reduced-privilege service or container-like admin as possible. This raises the practical triage score to 2.
* No local unprivileged trigger is awarded because ordinary unprivileged users normally cannot create or control table-less DM devices.

Not awarded:

* No remote/network trigger.
* No UAF, OOB write, double free, type confusion, refcount issue, or arbitrary write.
* No privilege escalation plausibility.
* No confidentiality or integrity impact.
* No security-boundary bypass. The observed primitive is NULL dereference DoS only.

## 3. Reachability analysis

The bug is locally reachable only if some actor can cause `dm_verity_loadpin_is_bdev_trusted()` to inspect a device-mapper block device that has no live table. In normal deployments, creating or manipulating that state requires CAP_SYS_ADMIN through device-mapper control paths, so the conservative interpretation is privileged local DoS. Namespaces or containers usually do not expose host device-mapper control to untrusted users, but some appliance or service configurations may delegate limited DM management, which justifies the paranoid score. The path is not network reachable.

Call-site confidence: medium. The patch clearly shows the NULL dereference condition, but the exact external trigger path depends on product-specific LoadPin and device-mapper configuration.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like kernel issue rather than an Important-class vulnerability. The theoretical impact is a kernel crash if the NULL table state is reached. Realistic exploitation evidence supports DoS only, not memory corruption, privilege escalation, information disclosure, or policy bypass. The issue does not require manual escalation unless the evaluated product exposes device-mapper control to less trusted local actors.

## 5. One-sentence report phrase

A missing NULL check in the dm-verity LoadPin helper can let a local privileged or delegated device-mapper actor trigger a kernel NULL-pointer dereference when a DM device has no live table, causing denial of service only.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be auto-closed for urgent triage because it is a local NULL-pointer DoS with typical admin-only reachability and no evidence of memory corruption, LPE, network exposure, or sensitive-object access.

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

Patch: dm-verity: fix a possible NULL pointer dereference commit e72b793ae440f6900fb17a4b8518c707b5cd3e17 upstream.
Commit: 7d4f1d307ac0f4f55cebeb192a90a235aa060ed1
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7d4f1d307ac0f4f55cebeb192a90a235aa060ed1

Commit description:

Fix a possible NULL pointer dereference dm_verity_loadpin_is_bdev_trusted
if the device has no table.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Assisted-by: Claude:claude-opus-4-6
Fixes: b6c1c5745ccc ("dm: Add verity helpers for LoadPin")
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat -rw-r--r-- drivers/md/dm-verity-loadpin.c 2

Changed files:
  drivers/md/dm-verity-loadpin.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=7d4f1d307ac0f4f55cebeb192a90a235aa060ed1

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

The original Linux kernel CVE announcement for CVE-2026-72097 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72097

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:H/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: 0
  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: 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 alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).