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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-98079
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-25 11:17:37 UTC
Updated2026-09-30 14:10:59 UTC
DescriptionIn 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.

Risk And Classification

EPSS: 0.001980000 probability, percentile 0.085850000 (date 2026-09-27)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 d8f57049521948df5f50797141472fbbed3b0723 git Not specified
CNA Linux Linux affected 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 0de9f31d447ae71ab08c7850a321682f8d2907c3 git Not specified
CNA Linux Linux affected 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7 git Not specified
CNA Linux Linux affected 5.1 Not specified
CNA Linux Linux unaffected 5.1 semver Not specified
CNA Linux Linux unaffected 6.18.53 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.7 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/0de9f31d447ae71ab08c7850a321682f8d2907c3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d8f57049521948df5f50797141472fbbed3b0723 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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