CVE-2026-98079 (GCVE-0-2026-98079)
Vulnerability from cvelistv5
Published
2026-09-25 10:24
Modified
2026-10-21 12:54
Severity ?
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.
References
Impacted products
Vendor Product Version
Linux Linux Version: 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96
Version: 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96
Version: 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96
Version: 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96
Version: 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96
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{
  "containers": {
    "cna": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/btrfs/zstd.c"
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          "vendor": "Linux",
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              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
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      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:54:23.769Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/14d982762945d9945c60bbd48b77df194dd8e28d"
        },
        {
          "url": "https://git.kernel.org/stable/c/844603cf842ee67640d33f350e3fa60f3de7fad3"
        },
        {
          "url": "https://git.kernel.org/stable/c/d8f57049521948df5f50797141472fbbed3b0723"
        },
        {
          "url": "https://git.kernel.org/stable/c/0de9f31d447ae71ab08c7850a321682f8d2907c3"
        },
        {
          "url": "https://git.kernel.org/stable/c/2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7"
        }
      ],
      "title": "btrfs: zstd: fix lost wakeup when waiting for a workspace",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98079",
    "datePublished": "2026-09-25T10:24:16.892Z",
    "dateReserved": "2026-09-25T10:19:56.074Z",
    "dateUpdated": "2026-10-21T12:54:23.769Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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