FKIE_CVE-2026-90276

Vulnerability from fkie_nvd - Published: 2026-09-17 17:17 - Updated: 2026-09-17 17:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: md/md-llbitmap: stop daemon timer rearm on destroy llbitmap_destroy() deletes pending_timer before flushing md_llbitmap_io_wq. However, daemon_work can still be queued or running after the timer has been deleted, and the daemon path can arm pending_timer again when it finds dirty chunks that are not ready to flush yet. If that happens during teardown, pending_timer can remain armed after llbitmap is freed and later dereference freed memory. Add a BITMAP_SHUTDOWN bit to llbitmap->flags, set it before deleting the timer, and make the timer and daemon paths stop queueing or rearming work once teardown starts. Cancel daemon_work before flushing the shared workqueue so no already queued daemon instance can race with the free. Use timer_shutdown_sync() so a daemon instance that passed the shutdown check before teardown cannot rearm the timer afterward. BITMAP_SHUTDOWN is a runtime-only state. Mask it out when reading and updating the llbitmap superblock so the shutdown state is never loaded from disk or persisted to disk.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5553d64e01d9a995be6c3de38501c6dd4ceede3b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/bb7f92d58fca9a9f06f3f51a82481c5f0bbbd46c
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c55aa6c17f019b6296952d336939891efa084c06
Impacted products
Vendor Product Version
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{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/md/md-bitmap.h",
            "drivers/md/md-llbitmap.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c55aa6c17f019b6296952d336939891efa084c06",
              "status": "affected",
              "version": "5ab829f1971dc99f2aac10846c378e67fc875abc",
              "versionType": "git"
            },
            {
              "lessThan": "bb7f92d58fca9a9f06f3f51a82481c5f0bbbd46c",
              "status": "affected",
              "version": "5ab829f1971dc99f2aac10846c378e67fc875abc",
              "versionType": "git"
            },
            {
              "lessThan": "5553d64e01d9a995be6c3de38501c6dd4ceede3b",
              "status": "affected",
              "version": "5ab829f1971dc99f2aac10846c378e67fc875abc",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/md/md-bitmap.h",
            "drivers/md/md-llbitmap.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.18"
            },
            {
              "lessThan": "6.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmd/md-llbitmap: stop daemon timer rearm on destroy\n\nllbitmap_destroy() deletes pending_timer before flushing\nmd_llbitmap_io_wq. However, daemon_work can still be queued or running\nafter the timer has been deleted, and the daemon path can arm\npending_timer again when it finds dirty chunks that are not ready to\nflush yet.\n\nIf that happens during teardown, pending_timer can remain armed after\nllbitmap is freed and later dereference freed memory.\n\nAdd a BITMAP_SHUTDOWN bit to llbitmap-\u003eflags, set it before deleting\nthe timer, and make the timer and daemon paths stop queueing or rearming\nwork once teardown starts. Cancel daemon_work before flushing the shared\nworkqueue so no already queued daemon instance can race with the free.\nUse timer_shutdown_sync() so a daemon instance that passed the shutdown\ncheck before teardown cannot rearm the timer afterward.\n\nBITMAP_SHUTDOWN is a runtime-only state. Mask it out when reading and\nupdating the llbitmap superblock so the shutdown state is never loaded\nfrom disk or persisted to disk."
    }
  ],
  "id": "CVE-2026-90276",
  "lastModified": "2026-09-17T17:17:24.247",
  "metrics": {},
  "published": "2026-09-17T17:17:24.247",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5553d64e01d9a995be6c3de38501c6dd4ceede3b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/bb7f92d58fca9a9f06f3f51a82481c5f0bbbd46c"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c55aa6c17f019b6296952d336939891efa084c06"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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