* [CVE-2026-80730][LOW] ring-buffer: Fix crash passing ERR_PTR to kthread_stop()
@ 2026-09-03 9:17 21% AL-KERNEL
0 siblings, 0 replies; 1+ results
From: AL-KERNEL @ 2026-09-03 9:17 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-80730
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: ring-buffer: Fix crash passing ERR_PTR to kthread_stop()
Commit: 51d78fad30dd9ae45721224103662bdbcf210096
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=51d78fad30dd9ae45721224103662bdbcf210096
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80730
Analysis date: Thu, 03 Sep 2026 05:17:16 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-80730 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80730
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-2026-80730 LOW https://www.kernelcve.org/list/?q=CVE-2026-80730 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-476;CWE-754;CWE-252;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'ring buffer self test cleanup can pass an ERR_PTR returned by kthread_run_on_cpu to kthread_stop when thread creation fails during late init. This causes kthread_stop to dereference an invalid pointer and can panic the kernel during boot or self test initialization. For the CVSS the PR:H is typical because reliable triggering requires administrative control over boot time test execution or system resource conditions before normal user workloads exist. The issue is not network reachable and is not exposed through normal packet or syscall processing after boot. Impact is denial of service only via kernel panic, with no plausible confidentiality or integrity impact from the shown primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 0) SKIP CVE-2026-80730 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES NO NO unknown MAYBE NULLPTR TRACE HARDWARE LINUS TEST - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=0
1. ActionableScore
* Conservative score: 0
* Paranoid score: 0
* Final recommended bucket: **Ordinary Moderate / Low-like**::
2. Signal breakdown
* Reliable kernel crash / strong DoS: +1. The patch and log show `kthread_stop()` dereferencing an `ERR_PTR`, causing Oops and kernel panic.
* Hard or unreliable race / special condition: -1. Triggering requires `kthread_run_on_cpu()` failure during the late init ring-buffer self-test cleanup path.
* Requires admin/root/boot control in typical deployments: -2. Reliable triggering depends on boot-time test execution or controlled early resource-failure conditions, not normal local user activity.
* Legacy / non-default execution mode: -1. This is a late-init self-test path, not a normal runtime tracing data path.
* No generic memory corruption signal. This is an invalid pointer dereference of an `ERR_PTR`, not UAF, OOB write, double-free, or controlled object reuse.
* No confidentiality or integrity impact. No disclosure, write primitive, object confusion, or privilege escalation path is supported by the patch.
3. Reachability analysis
The bug is reached during `test_ringbuffer()` at late init when thread creation fails for a CPU and cleanup calls `kthread_stop()` on an `ERR_PTR`. It is not network reachable and is not exposed through normal syscalls, tracing operations, packet processing, or namespace/container interfaces after boot. Namespaces do not meaningfully lower the privilege requirement because the relevant path runs during kernel initialization. Realistic exploitation requires unusual boot/test configuration plus resource failure timing.
4. Severity interpretation
This behaves like a boot-time reliability DoS, not an Important-class vulnerability. The demonstrated impact is kernel panic only. The theoretical class is invalid pointer dereference, but there is no realistic evidence of attacker-controlled memory corruption, reclaim, callback control, information disclosure, or privilege escalation. It should be treated as ordinary Moderate / Low-like for practical triage.
5. One-sentence report phrase
The ring-buffer startup self-test cleanup path could pass an `ERR_PTR` from a failed `kthread_run_on_cpu()` call into `kthread_stop()`, causing a boot-time kernel panic under special failure conditions.
6. Manual review recommendation
NO MANUAL CHECK NEEDED. This is a constrained boot-time DoS-only crash with no network exposure, no normal unprivileged trigger, and no supported memory corruption or privilege escalation primitive.
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: ring-buffer: Fix crash passing ERR_PTR to kthread_stop()
Commit: 51d78fad30dd9ae45721224103662bdbcf210096
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=51d78fad30dd9ae45721224103662bdbcf210096
Commit description:
In test_ringbuffer()'s out_free cleanup loop, the check
`!rb_threads[cpu]` only catches NULL entries and misses entries that
hold an ERR_PTR.
rb_threads[] is static, so unassigned slots are NULL. But when
kthread_run_on_cpu() fails for a cpu, it stores ERR_PTR(-ENOMEM) (or
-EINTR) in rb_threads[cpu] before the creation loop jumps to out_free.
That entry is non-NULL, so the old `!ptr` check does not break, and the
cleanup proceeds to call kthread_stop() on the ERR_PTR. kthread_stop()
then dereferences the bogus pointer, crashing the kernel during the
late_initcall self-test.
crash logs:
BUG: kernel NULL pointer dereference, address: 000000000000001c
Oops: 0002 [#1] SMP NOPTI
CPU: 1 PID: 1 Comm: swapper/0 Not tainted 7.2.0-rc6-dirty #7 PREEMPT(lazy)
RIP: 0010:kthread_stop+0x2e/0x220
RBX: fffffffffffffff4
CR2: 000000000000001c
Call Trace:
<TASK>
test_ringbuffer+0x1ec/0x650
do_one_initcall+0x6c/0x2c0
kernel_init_freeable+0x21d/0x420
kernel_init+0x15/0x1c0
ret_from_fork+0x21b/0x320
</TASK>
Kernel panic - not syncing: Fatal exception
Cc: [email protected]
Fixes: 64ed3a0 ("ring-buffer: make use of the helper function kthread_run_on_cpu()")
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Hui Su <[email protected]>
Reviewed-by: Vincent Donnefort <[email protected]>
Acked-by: Masami Hiramatsu (Google) <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
kernel/trace/ring_buffer.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=51d78fad30dd9ae45721224103662bdbcf210096
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-80730 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80730
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:H
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: unknown
Paranoid ActionableScore: 0
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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