btrfs: zstd: fix lost wakeup when waiting for a workspace
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 1 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
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.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.6.160, 6.12.114, 6.18.53, 7.2.7, 7.3
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
Not affected: 6 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4
- Red Hat OpenShift Container Platform 5
Timeline
- 2026-10-02 Threatist record created from CVE-2026-98079
- 2026-10-03 Alias added: GHSA-4xrv-jf38-655f
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-21 Affected versions changed · Red Hat
- 2026-10-21 CVSS score added · Red Hat
- 2026-10-21 Fix available: Linux/Linux@14d982762945d9945c60bbd48b77df194dd8e28d, Linux/[email protected], Linux/[email protected] +1 · CNA
- 2026-10-21 2 new references · CNA
- 2026-11-07 Affected versions changed · Red Hat
References
Other 5
- https://git.kernel.org/stable/c/14d982762945d9945c60bbd48b77df194dd8e28d
- https://git.kernel.org/stable/c/844603cf842ee67640d33f350e3fa60f3de7fad3
- https://git.kernel.org/stable/c/d8f57049521948df5f50797141472fbbed3b0723
- https://git.kernel.org/stable/c/0de9f31d447ae71ab08c7850a321682f8d2907c3
- https://git.kernel.org/stable/c/2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7
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Sources
- CVE-2026-98079 · CVE Program
- CVE-2026-98079 · NVD
- FIRST EPSS
- GHSA-4xrv-jf38-655f · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98079 · Red Hat security data · CC BY 4.0
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