[CVE-2026-72298][IMPORTANT] net: qrtr: fix 32-bit integer overflow in qrtr_endpoint_post()

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

CVE: CVE-2026-72298
Priority: IMPORTANT
AL-KERNEL base severity: IMPORTANT
KPANIC flag: YES
Patch: net: qrtr: fix 32-bit integer overflow in qrtr_endpoint_post()
Commit: 3665e644ea081c4624a1637023b0de3b29f4ae04
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3665e644ea081c4624a1637023b0de3b29f4ae04
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72298
Analysis date: Sun, 16 Aug 2026 08:43:12 -0400
ActionableScore: 8
ActionableScore lower bound: 5
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A 32-bit integer overflow in `qrtr_endpoint_post()` allows a malformed incoming QRTR packet to bypass length validation and trigger an out-of-bounds `skb_put_data()` write, causing a kernel crash and warranting manual review for possible broader memory-corruption impact.

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

The original Linux kernel CVE announcement for CVE-2026-72298 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72298

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: IMPORTANT
Manual review required: YES

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-2026-72298	IMPORTANT	CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H';CWE-190;*CWE-787;*CWE-20;Other CVSS 'AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '8.8';DESCR 'A 32-bit integer overflow in qrtr_endpoint_post can let a malformed incoming QRTR packet bypass the length check when ALIGN(size, 4) wraps to zero. The code can then call skb_put_data() with an attacker controlled very large size and write past the allocated skb buffer, causing kernel memory corruption and a likely crash. For the CVSS the PR:N is used for the paranoid score because the packet size comes from the wire and no victim local account is required if an attacker can reach the QRTR endpoint or adjacent transport. The issue is not a normal public Internet AV:N case and is better modeled as AV:A because QRTR is typically exposed through local or adjacent device transports. Impact is at least denial of service via kernel crash and in the worst case may allow confidentiality or integrity impact due to kernel out-of-bounds write.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7)	YES	OOB SIMPLEFIX SKB LINUS PACKET  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS8.5PLUS	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=8
ActionableScoreLower=5

## 1. ActionableScore

* Conservative score: 5
* Paranoid score: 8
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* +1 Firmware-mediated external influence. The malformed QRTR packet comes from an external or adjacent QRTR transport endpoint rather than a normal local syscall path.
* +2 Memory corruption, strong corruption primitive. The integer overflow allows `skb_put_data()` to copy a very large wire-controlled size past a small skb buffer.
* +1 Memory layout invariant restoration. The fix restores consistency between `size`, `len`, `ALIGN(size, 4)`, and `hdrlen` before skb buffer construction.
* +1 Reliable kernel crash / strong DoS. The commit explicitly says the overflow writes past the skb and oopses the kernel on 32-bit systems.

Paranoid additions:

* +1 Exposure upgraded from firmware-mediated to transport/network-triggerable. If an attacker can directly reach the affected QRTR endpoint or adjacent transport, no local victim account is required.
* +1 Confidentiality impact plausible. Kernel OOB write can theoretically corrupt adjacent kernel objects and may support disclosure in a stronger exploit chain.
* +1 Integrity impact plausible. Kernel OOB write can theoretically modify adjacent kernel state, so integrity impact is defensible for paranoid triage.

No subtraction applied for rarity in the final score because QRTR is niche, but on affected 32-bit QRTR deployments the path is an ordinary receive-side parser and the bug is directly in packet validation.

## 3. Reachability analysis

The bug is triggered by a malformed incoming QRTR packet whose `size` field is taken from the wire. It affects only 32-bit kernels because `size_t` wrapping is required for `ALIGN(size, 4)` to become zero. This is not a normal public Internet `AV:N` exposure, but it is realistic for adjacent, firmware-mediated, or device-transport attackers that can inject QRTR frames into the affected endpoint. Namespaces are not the main factor here because the vulnerable path is below ordinary local process privilege checks.

Call-site confidence: high. The commit directly identifies the failing check and the downstream `skb_put_data()` OOB write.

## 4. Severity interpretation

This is stronger than an ordinary Moderate because the primitive is not just a warning or NULL dereference. It is an integer-overflow-driven kernel out-of-bounds write in a networking receive path. Realistically, the most demonstrated impact is a 32-bit kernel crash. The paranoid interpretation treats it as a Strong Important candidate because kernel OOB writes can sometimes be exploitable beyond DoS, even though no reliable privilege-escalation exploit is demonstrated here.

## 5. One-sentence report phrase

A 32-bit integer overflow in `qrtr_endpoint_post()` allows a malformed incoming QRTR packet to bypass length validation and trigger an out-of-bounds `skb_put_data()` write, causing a kernel crash and warranting manual review for possible broader memory-corruption impact.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: this is a concrete kernel OOB write in a packet parser with external or adjacent input influence, not merely a DoS-only validation bug.

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

Patch: net: qrtr: fix 32-bit integer overflow in qrtr_endpoint_post()
Commit: 3665e644ea081c4624a1637023b0de3b29f4ae04
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3665e644ea081c4624a1637023b0de3b29f4ae04

Commit description:

qrtr_endpoint_post() validates an incoming packet with

	if (!size || len != ALIGN(size, 4) + hdrlen)
		goto err;

where size comes from the wire. On 32-bit, size_t is 32 bits and
ALIGN(size, 4) wraps to 0 for size >= 0xfffffffd, so the check
passes and skb_put_data(skb, data + hdrlen, size) writes past the
hdrlen-sized skb and oopses the kernel. 64-bit is unaffected.

This is the 32-bit residual of ad9d24c ("net: qrtr: fix OOB
Read in qrtr_endpoint_post"), which fixed only the 64-bit case.

Reject any size that cannot fit the buffer before the ALIGN.

Fixes: ad9d24c ("net: qrtr: fix OOB Read in qrtr_endpoint_post")
Cc: stable@vger.kernel.org
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260611125455.2352279-1-michael.bommarito@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  net/qrtr/af_qrtr.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=3665e644ea081c4624a1637023b0de3b29f4ae04

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

The original Linux kernel CVE announcement for CVE-2026-72298 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72298

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:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 8.8

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: 5
  Paranoid ActionableScore: 8

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: IMPORTANT
KPANIC detected for this report: YES
Published priority for this report (same as in Subject): IMPORTANT

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).