CVE-2026-98079btrfs: zstd: fix lost wakeup when waiting for a workspace
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- Not yet scored
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Undergoing Analysis
- Record last updated
- Sep 25, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 before d8f57049521948df5f50797141472fbbed3b0723; 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 builds before 0de9f31d447ae71ab08c7850a321682f8d2907c3; 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 builds before 2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7 | CNA record |
References
- https://git.kernel.org/stable/c/d8f57049521948df5f50797141472fbbed3b0723
- https://git.kernel.org/stable/c/0de9f31d447ae71ab08c7850a321682f8d2907c3
- https://git.kernel.org/stable/c/2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.