btrfs: zstd: fix lost wakeup when waiting for a workspace (CVE-2026-98079) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-98079

btrfs: zstd: fix lost wakeup when waiting for a workspace

Answer in brief

CVE-2026-98079 records a Unknown severity vulnerability in btrfs: zstd: fix lost wakeup when waiting for a workspace. 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 25, 2026Updated Sep 25, 2026Source checked Sep 25, 2026First seen by HOL Sep 25, 2026Material review Sep 25, 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	>=3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 <d8f57049521948df5f50797141472fbbed3b0723 \|\| >=3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 <0de9f31d447ae71ab08c7850a321682f8d2907c3 \|\| >=3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 <2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7	d8f57049521948df5f50797141472fbbed3b0723, 0de9f31d447ae71ab08c7850a321682f8d2907c3, 2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7
Linux/Linuxgeneric	5.1	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to d8f57049521948df5f50797141472fbbed3b0723 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 25, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: btrfs: zstd: fix lost wakeup when waiting for a workspace A writer can sleep forever in zstd_get_workspace() even though a workspace is free. When zstd_alloc_workspace() fails, the task is queued on zwsm->wait and schedules unconditionally, never re-testing the pool. zstd_put_workspace() publishes the workspace and then calls cond_wake_up(), which only wakes when a sleeper is already visible, so a workspace returned between the failed allocation and prepare_to_wait() wakes nobody. The window is wide: zstd_alloc_workspace() goes through kvmalloc() and may enter reclaim. Only a max level workspace triggers the wakeup and one is deliberately kept allocated as the fallback every waiter waits for, so once its wakeup is lost the writer stays in TASK_UNINTERRUPTIBLE until some other task happens to return one. Re-check the pool after prepare_to_wait() has published the waiter, and use the workspace if one turned up.

Quoted source text, attributed separately from HOL analysis.