[CVE-2026-80865][MODERATE REGULAR] bpf: Add missing access_ok call to copy_user_syms

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

CVE: CVE-2026-80865
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: bpf: Add missing access_ok call to copy_user_syms
Commit: a67f7f9647cb243b3be32163e88e5bc76e3d51e9
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a67f7f9647cb243b3be32163e88e5bc76e3d51e9
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80865
Analysis date: Fri, 04 Sep 2026 18:43:23 -0400
ActionableScore: 3
ActionableScore lower bound: 1
Actionable bucket: Borderline, manual review recommended / not an Important candidate by current evidence
Manual review required: YES

Summary:
`copy_user_syms used __get_user on a user supplied BPF symbol pointer array without prior access_ok validation, creating an unsafe local uaccess path with possible limited confidentiality impact, but typical exploitation requires privileged BPF tracing access and is not network reachable.`

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-80865 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80865

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 REGULAR
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-2026-80865	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-80865 CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L';*CWE-20;CWE-125;*CWE-200;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '5.3';DESCR 'copy_user_syms used __get_user on the user supplied symbol pointer array without first validating the full array with access_ok. This can allow a local actor with access to BPF kprobe multi link setup to provide an invalid or non user pointer array and reach an unsafe user access path. For the CVSS the PR:L is used because reliable triggering requires local execution with BPF tracing related privileges or delegated capabilities, but not necessarily full host administrator control in all deployments. The issue is not network reachable. Impact is primarily limited confidentiality exposure through improper user pointer validation, with possible limited integrity or availability effects in the paranoid interpretation. YES REQUIRES MANUAL CHECK';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended / not an Important candidate by current evidence (with actual score 2)	YES	TRACE BPF NOMEMCHK SIMPLEFIX ERRORPATH IMPROVEONLY LINUS  INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	YES	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=3
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: 1
* Paranoid score: 3
* Final recommended bucket: **Borderline, manual review recommended / not an Important candidate by current evidence**

## 2. Signal breakdown

Conservative signals:

* Confidentiality impact plausible: +1. Missing `access_ok()` before `__get_user()` may allow an unsafe user-access path and limited pointer-sized kernel memory probing on some architectures or configurations.
* Requires admin/root/CAP_* in typical deployments: -2. This BPF kprobe multi path normally requires privileged BPF/tracing capabilities such as CAP_BPF, CAP_PERFMON, CAP_SYS_ADMIN, or equivalent root-controlled configuration.
* No remote reachable signal. This is a local BPF tracing setup path.
* No generic memory corruption signal. The patch does not show UAF, OOB write, double free, type confusion, refcount misuse, or arbitrary write.
* No reliable kernel crash signal. The commit describes missing validation, not a demonstrated panic or Oops.

Paranoid signals:

* Confidentiality impact plausible: +1.
* Weak/indirect unsafe access concern: +1. `__get_user()` is used on a user supplied pointer array without the expected prior range validation.
* Security sensitive BPF tracing path requiring manual review: +1. Even though privileged, BPF tracing bugs deserve review because the API can involve user controlled symbol arrays and kernel lookup behavior.
* Privilege penalty still applies in the conservative interpretation, but the paranoid score keeps the issue at manual-review level because unsafe uaccess bugs can be architecture dependent.

## 3. Reachability analysis

The likely trigger is a local process that can create a BPF kprobe multi link and pass a crafted `usyms` pointer array into `copy_user_syms()`. In typical hardened or enterprise configurations, unprivileged BPF is disabled and this path is gated by capabilities or root-controlled settings, so this is not a true unprivileged local trigger. Namespaces may matter only if BPF/tracing capabilities are delegated into a container or reduced-capability service context. The path is not network reachable.

Call-site confidence: medium. The patch shows the vulnerable helper and its BPF tracing context, but not all callers or product-specific BPF privilege policy.

## 4. Severity interpretation

This behaves like a low-to-borderline Moderate issue rather than an Important-class vulnerability. The realistic evidence supports improper user pointer validation with possible limited confidentiality impact, not a demonstrated memory corruption or LPE primitive. Theoretical risk is higher on architectures where missing `access_ok()` before `__get_user()` can meaningfully bypass user-range checks, but the patch does not demonstrate attacker-controlled overwrite, reclaim, callback control, or privilege escalation.

## 5. One-sentence report phrase

`copy_user_syms used __get_user on a user supplied BPF symbol pointer array without prior access_ok validation, creating an unsafe local uaccess path with possible limited confidentiality impact, but typical exploitation requires privileged BPF tracing access and is not network reachable.`

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: unsafe uaccess in BPF tracing is security-sensitive and architecture-dependent, but current evidence does not justify Important severity because the path is typically capability-gated and no concrete memory corruption or privilege-escalation primitive is shown.

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

Patch: bpf: Add missing access_ok call to copy_user_syms
Commit: a67f7f9647cb243b3be32163e88e5bc76e3d51e9
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a67f7f9647cb243b3be32163e88e5bc76e3d51e9

Commit description:

As reported by sashiko we use __get_user without prior access_ok call on the
user space pointer. Adding the missing call for the whole pointer array.

Plus removing the err check in the error path, because it's not needed and
also we can return -ENOMEM directly from the first kvmalloc_array fail path.

Cc: stable@vger.kernel.org
[1] https://lore.kernel.org/bpf/20260611115503.AC16D1F00893@smtp.kernel.org/
Fixes: 0236fec ("bpf: Resolve symbols with ftrace_lookup_symbols for kprobe multi link")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://lore.kernel.org/bpf/20260611115503.AC16D1F00893@smtp.kernel.org/
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260616083056.405652-1-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  kernel/trace/bpf_trace.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=a67f7f9647cb243b3be32163e88e5bc76e3d51e9

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

The original Linux kernel CVE announcement for CVE-2026-80865 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80865

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:L/UI:N/S:U/C:L/I:N/A:N
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
  The Best / paranoid CVSS score: 5.3

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: 3

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: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

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).