[CVE-2026-97606][LOW] fs: autofs: fix memory leak in autofs_fill_super()

[CVE-2026-97606][LOW] fs: autofs: fix memory leak in autofs_fill_super()

[AL-KERNEL]

CVE: CVE-2026-97606
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: fs: autofs: fix memory leak in autofs_fill_super()
Commit: 4262b91e08e74cb5209ea737c554cf983d332382
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4262b91e08e74cb5209ea737c554cf983d332382
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97606
Analysis date: Fri, 25 Sep 2026 12:24:51 -0400
ActionableScore: 2
ActionableScore lower bound: 1
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-2026-97606 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97606

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-2026-97606	LOW	https://www.kernelcve.org/list/?q=CVE-2026-97606 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:N/I:N/A:H';*CWE-401;*CWE-772;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'autofs_fill_super can leak an autofs inode information object when allocation of the root VFS inode fails after autofs_new_ino has already succeeded. Repeated failed mount attempts under memory pressure could gradually consume kernel memory, although a single failure leaks only a small object and does not directly crash the system. For the CVSS the PR:L in the paranoid score accounts for user namespaces, container root, or delegated mount helpers that may permit a limited local user to initiate autofs mount operations. Reliable triggering also depends on reaching the root inode allocation failure path, so AC:H is appropriate. The issue is not network reachable. Impact is limited to availability through resource exhaustion, with no UAF, OOB access, information disclosure, or write primitive supported by the affected path.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)  SKIP CVE-2026-97606 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES  NO NO unknown 	MAYBE	DISK INIT SIMPLEFIX LEAK LINUS SYZBOT 	-	-	checked

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

ActionableScore=2
ActionableScoreLower=1
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 2
* Paranoid score: 2
* No floor or cap was applied.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

Conservative signals:

* +1 Concrete persistent kernel resource leak. `autofs_new_ino()` allocates `ino`, but the `root_inode` allocation failure returned `-ENOMEM` without calling `autofs_free_ino()`.
* No negative points. The required mount privilege and namespace scope are unresolved, so no speculative privilege penalty is applied.

Paranoid additional signal:

* +1 Availability through cumulative resource exhaustion. Repeated failed mount attempts could accumulate leaked objects, although this requires repeatedly reaching the allocation-failure path and no immediate host-wide exhaustion is demonstrated.

Not awarded:

* No UAF, double release, stale reference, OOB access, arbitrary write, disclosure, or authorization bypass.
* No reliable kernel crash point because the documented result is a small leak on an existing `-ENOMEM` path.
* No remote or ordinary-unprivileged reachability bonus is established.
* No confidentiality, integrity, LPE, or Important-grade exploitation leverage.
* No race penalty. This is an ordered allocation error path, not a timing race.

3. Reachability analysis

The trigger requires invoking `autofs_fill_super()` and then causing `autofs_get_inode()` to fail after `autofs_new_ino()` succeeds. The supplied evidence does not establish whether the complete mount operation requires host-admin-equivalent privilege or can be completed through an attacker-created user namespace, delegated mount helper, or container capability. Therefore, both host-admin and namespace-scoped privilege status remain unknown.

The path is local and not network reachable. It requires autofs support and an allocation failure, normally associated with memory pressure or fault injection. There is no special hardware or race requirement. Practical accumulation also requires repeated mount attempts that consistently reach the narrow allocation-failure window.

4. Primitive and severity interpretation

The exact defect is a missing cleanup operation for an allocated autofs inode-information object. The object becomes unreachable when `autofs_fill_super()` returns `-ENOMEM`, producing a persistent kernel memory leak.

This is not a post-lifetime access. No dangling object is dereferenced or modified, and no second release or refcount mutation exists. Consequently, `RealUAF=NO` and `PrimitiveClass=NONE`.

The demonstrated consequence is loss of a small allocation. Gradual resource exhaustion is a defensible paranoid consequence, but immediate kernel failure, cross-boundary consumption, accounting bypass, or privilege escalation is not established. The issue is not an Important candidate and can be automatically downgraded.

5. One-sentence report phrase

A failed autofs root inode allocation leaks the previously allocated inode information object, allowing limited cumulative kernel memory consumption through repeated local mount failures without establishing memory corruption or privilege escalation.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch establishes only a small error-path resource leak, with no UAF, corruption, security-boundary bypass, or meaningful unresolved exploitation primitive.

7. Call-site confidence

Call-site confidence: high

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

Patch: fs: autofs: fix memory leak in autofs_fill_super()
Commit: 4262b91e08e74cb5209ea737c554cf983d332382
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4262b91e08e74cb5209ea737c554cf983d332382

Commit description:

In autofs_fill_super(), we create a new inode using
autofs_new_ino(), however, if we fail to create root_inode,
(that is, root_inode failure path), we return -ENOMEM without
freeing the new inode(ino) that we created causing a memory leak.
Fix this by adding autofs_free_ino() to free the inode we created
in root_inode failure path before returning ENOMEM.

Reported-by: syzbot+df1db6e034b3953e19f5@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=df1db6e034b3953e19f5
Fixes: 66917f8 ("autofs: add: new_inode check in autofs_fill_super()")
Cc: stable@vger.kernel.org
Signed-off-by: Jeffin Philip <jeffinphilip14@gmail.com>
Link: https://patch.msgid.link/20260903081048.132524-1-jeffinphilip14@gmail.com
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  fs/autofs/inode.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=4262b91e08e74cb5209ea737c554cf983d332382

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

The original Linux kernel CVE announcement for CVE-2026-97606 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97606

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: 1
  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).