{"id":"CVE-2026-98079","summary":"btrfs: zstd: fix lost wakeup when waiting for a workspace","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: zstd: fix lost wakeup when waiting for a workspace\n\nA writer can sleep forever in zstd_get_workspace() even though a workspace\nis free.  When zstd_alloc_workspace() fails, the task is queued on\nzwsm-\u003ewait and schedules unconditionally, never re-testing the pool.\nzstd_put_workspace() publishes the workspace and then calls cond_wake_up(),\nwhich only wakes when a sleeper is already visible, so a workspace returned\nbetween the failed allocation and prepare_to_wait() wakes nobody.  The\nwindow is wide: zstd_alloc_workspace() goes through kvmalloc() and may\nenter reclaim.\n\nOnly a max level workspace triggers the wakeup and one is deliberately kept\nallocated as the fallback every waiter waits for, so once its wakeup is\nlost the writer stays in TASK_UNINTERRUPTIBLE until some other task happens\nto return one.  Re-check the pool after prepare_to_wait() has published the\nwaiter, and use the workspace if one turned up.","modified":"2026-09-26T03:48:28.170493146Z","published":"2026-09-25T10:24:16.892Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98079.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/0de9f31d447ae71ab08c7850a321682f8d2907c3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d8f57049521948df5f50797141472fbbed3b0723"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98079.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98079"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"3f93aef535c8ea03e40cd8acf0753b3e6ed33e96"},{"fixed":"d8f57049521948df5f50797141472fbbed3b0723"},{"fixed":"0de9f31d447ae71ab08c7850a321682f8d2907c3"},{"fixed":"2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98079.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.1.0"},{"fixed":"6.18.53"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98079.json"}}],"schema_version":"1.9.0"}