samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify (CVE-2026-90066) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-90066

samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify

Answer in brief

CVE-2026-90066 records a Unknown severity vulnerability in samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 17, 2026Updated Sep 17, 2026Source checked Sep 17, 2026First seen by HOL Sep 17, 2026Material review Sep 17, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=e1067a07cfbc5a36abad3752fafe4c79e06db1bb <7a96b9f6d5ba23dbce66c8a4a242effd4c01a830 \|\| >=e1067a07cfbc5a36abad3752fafe4c79e06db1bb <98b7b2a29ae87937aa02ab9391543ef8c602cd94 \|\| >=e1067a07cfbc5a36abad3752fafe4c79e06db1bb <626614df9080d7052fbe24dc90b5434717ab7a9f \|\| >=e1067a07cfbc5a36abad3752fafe4c79e06db1bb <cf839636911d8313f3ecd098329fd0b96499e4cf \|\| >=e1067a07cfbc5a36abad3752fafe4c79e06db1bb <6727b7618f49401acf373fa3ec5712e2ec52e5cf	7a96b9f6d5ba23dbce66c8a4a242effd4c01a830, 98b7b2a29ae87937aa02ab9391543ef8c602cd94, 626614df9080d7052fbe24dc90b5434717ab7a9f, cf839636911d8313f3ecd098329fd0b96499e4cf, 6727b7618f49401acf373fa3ec5712e2ec52e5cf
Linux/Linuxgeneric	5.16	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 7a96b9f6d5ba23dbce66c8a4a242effd4c01a830 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 17, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify ftrace_direct_multi_init() assigns kthread_run()'s return value to simple_tsk without an IS_ERR() check. When kthread_run() fails it returns ERR_PTR(-ENOMEM), but init still returns 0, so the module loads with simple_tsk holding an error pointer. On unload, ftrace_direct_multi_exit() then passes that ERR_PTR to kthread_stop(), leading to a null-pointer-dereference. Check the return value of kthread_run() with IS_ERR(); on failure, unregister the ftrace direct call and propagate the error code.

Quoted source text, attributed separately from HOL analysis.