[CVE-2026-72178][LOW] mm/damon/core: always put unsuccessfully committed target pids

[CVE-2026-72178][LOW] mm/damon/core: always put unsuccessfully committed target pids

[AL-KERNEL]

CVE: CVE-2026-72178
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: YES
Patch: mm/damon/core: always put unsuccessfully committed target pids
Commit: ea07e045611ca00f1ec7e448fd43e655d311158b
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ea07e045611ca00f1ec7e448fd43e655d311158b
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72178
Analysis date: Sun, 16 Aug 2026 07:19:04 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A failed DAMON context commit can leak `struct pid` references after partially committed target state, causing a local resource-exhaustion DoS only in uncommon privileged or delegated DAMON control scenarios.

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

The original Linux kernel CVE announcement for CVE-2026-72178 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72178

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-2026-72178	LOW	CHECK WITH IMPACT FROM ORIG NN NONE	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-401;*CWE-772;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'DAMON context commit can leak struct pid references when a target commit fails after some pids were already copied into the destination context and the destination context has no cleanup_target callback. This is a resource leak in an uncommon error path rather than a direct memory corruption primitive. For the CVSS the PR:L is used for the paranoid score because a delegated local management process or reduced capability service with access to DAMON control interfaces could potentially trigger repeated failed commits, while normal deployments usually restrict this to administrators. The issue is not network reachable and requires local control plane access to DAMON configuration. Impact is denial of service through accumulated resource leakage, with no concrete evidence of information disclosure or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)  SKIP CVE-2026-72178 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: 83dc7bbaecae6e69e338355e9a137f0e7a0ecc40 YES  NO NO unknown 	MAYBE	OOB NOMEMCHK LINUS KPANIC MEMORY 	-	-	checked

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

ActionableScore=1
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate / Low-like**

## 2. Signal breakdown

Conservative signals:

* Availability impact realistic: +1. The leaked `struct pid` references can accumulate and may eventually cause resource exhaustion, but this requires repeated failed DAMON context commits.
* Requires admin/root/CAP_* in typical deployments: -2. DAMON control is normally exposed through privileged sysfs/debugfs style management paths and is not a normal unprivileged user API.
* Rare AND difficult-to-reach subsystem/configuration: -1. The problematic path requires DAMON context commit, a destination context without `cleanup_target`, source pid targets, and an error during or after partial target commit.
* Hard/special failure condition: -1. The commit message specifically points to allocation failure with a huge number of target regions as a realistic but non-common trigger.
* Score is floored at 0.

Paranoid signals:

* Local delegated trigger concern: +1. If a reduced-privilege service or delegated management component can control DAMON commits, the practical privilege model may be closer to PR:L than PR:H.
* Availability impact realistic: +1. Sustained triggering can leak pid references and cause resource pressure.
* Hard/special failure condition: -1. Triggering depends on an uncommon failed commit path, not a simple deterministic crash.
* No memory corruption, UAF, double-free, OOB write, info leak, or privilege escalation primitive is supported by the patch.

Call-site confidence: high. The patch includes the relevant commit, rollback, and cleanup logic in `damon_commit_targets()` and `damon_commit_ctx()`.

## 3. Reachability analysis

The bug is locally reachable only through DAMON control-plane operations. In normal deployments this is administrator-controlled, so conservative scoring treats it as PR:H. A paranoid interpretation can consider PR:L only when DAMON control is delegated to a local service, container management layer, or reduced-capability operator process.

The path is not network reachable. Namespaces do not obviously make this broadly unprivileged unless the product explicitly delegates DAMON management. The affected scenario is also uncommon because it requires a partial context commit failure after some pid references have already been transferred.

## 4. Severity interpretation

This behaves like a low-end Moderate or Low-like resource leak, not an Important-class vulnerability. The realistic impact is accumulated resource leakage and possible denial of service after repeated failed operations. There is no concrete evidence of memory corruption, stale pointer reuse, write-after-free, arbitrary write, information disclosure, or local privilege escalation.

The paranoid score remains low because it only changes the privilege interpretation from full admin to delegated local control and does not change the vulnerability class.

## 5. One-sentence report phrase

A failed DAMON context commit can leak `struct pid` references after partially committed target state, causing a local resource-exhaustion DoS only in uncommon privileged or delegated DAMON control scenarios.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This is a resource leak in an uncommon error path with no supported memory-corruption or privilege-escalation primitive, so it can be handled as ordinary delayed Moderate/Low-like maintenance unless the product delegates DAMON control to untrusted local users.

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

Patch: mm/damon/core: always put unsuccessfully committed target pids
Commit: ea07e045611ca00f1ec7e448fd43e655d311158b
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ea07e045611ca00f1ec7e448fd43e655d311158b

Commit description:

damon_commit_target() puts and gets the destination and the source target
pids.  It puts the destination target pid because it will be overwritten
by the source target pid.  It gets the source pid because the caller is
supposed to eventually put the pids.  In more detail, the caller will call
damon_destroy_ctx() after damon_commit_ctx() to destroy the entire source
context.  And in this case, [f]vaddr operation set's cleanup_target()
callback will put the pids.

The commit operation is made at the context level.  The operation can fail
in multiple places including in the middle and after the targets commit
operations.  For any such failures, immediately the error is returned to
the damon_commit_ctx() caller.  If some or all of the source target pids
were committed to the destination during the unsuccessful context commit
attempt, those pids should be put twice.

The source context will do the put operations using the above explained
routine.  However, let's suppose the destination context was not
originally using [f]vaddr operation set and the commit failed before the
ops of the source context is committed.  The destination does not have the
cleanup_target() ops callback, so it cannot put the pids via the
damon_destroy_ctx().

As a result, the pids are leaked.  The issue in the real world would be
not very common.  The commit feature is for changing parameters of running
DAMON context while inheriting internal status like the monitoring
results.  The monitoring results of a physical address range ain't have
things that are beneficial to be inherited to a virtual address ranges
monitoring.  So the problem-causing DAMON control would be not very common
in the real world.  That said, it is a supported feature.  And
damon_commit_target() failure due to memory allocation is relatively
realistic [1] if there are a huge number of target regions.

Fix by putting the pids in the commit operation in case of the failures.

The issue was discovered [2] by Sashiko.

Link: https://lore.kernel.org/20260605013849.83750-1-sj@kernel.org
Link: https://lore.kernel.org/20260603112306.58490-1-akinobu.mita@gmail.com [1]
Link: https://lore.kernel.org/20260320020056.835-1-sj@kernel.org [2]
Fixes: 83dc7bb ("mm/damon/sysfs: use damon_commit_ctx()")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 6.11.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  mm/damon/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=ea07e045611ca00f1ec7e448fd43e655d311158b

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

The original Linux kernel CVE announcement for CVE-2026-72178 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72178

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:L
  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: 0
  Paranoid ActionableScore: 1

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: YES
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).