fkie_cve-2025-39941
Vulnerability from fkie_nvd
Published
2025-10-04 08:15
Modified
2025-10-06 14:56
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: zram: fix slot write race condition Parallel concurrent writes to the same zram index result in leaked zsmalloc handles. Schematically we can have something like this: CPU0 CPU1 zram_slot_lock() zs_free(handle) zram_slot_lock() zram_slot_lock() zs_free(handle) zram_slot_lock() compress compress handle = zs_malloc() handle = zs_malloc() zram_slot_lock zram_set_handle(handle) zram_slot_lock zram_slot_lock zram_set_handle(handle) zram_slot_lock Either CPU0 or CPU1 zsmalloc handle will leak because zs_free() is done too early. In fact, we need to reset zram entry right before we set its new handle, all under the same slot lock scope.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ce4be9e4307c5a60701ff6e0cafa74caffdc54ce
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ff750e9f2c4d63854c33967d1646b5e89a9a19a2
Impacted products
Vendor Product Version


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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nzram: fix slot write race condition\n\nParallel concurrent writes to the same zram index result in leaked\nzsmalloc handles.  Schematically we can have something like this:\n\nCPU0                              CPU1\nzram_slot_lock()\nzs_free(handle)\nzram_slot_lock()\n\t\t\t\tzram_slot_lock()\n\t\t\t\tzs_free(handle)\n\t\t\t\tzram_slot_lock()\n\ncompress\t\t\tcompress\nhandle = zs_malloc()\t\thandle = zs_malloc()\nzram_slot_lock\nzram_set_handle(handle)\nzram_slot_lock\n\t\t\t\tzram_slot_lock\n\t\t\t\tzram_set_handle(handle)\n\t\t\t\tzram_slot_lock\n\nEither CPU0 or CPU1 zsmalloc handle will leak because zs_free() is done\ntoo early.  In fact, we need to reset zram entry right before we set its\nnew handle, all under the same slot lock scope."
    }
  ],
  "id": "CVE-2025-39941",
  "lastModified": "2025-10-06T14:56:47.823",
  "metrics": {},
  "published": "2025-10-04T08:15:47.103",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ce4be9e4307c5a60701ff6e0cafa74caffdc54ce"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ff750e9f2c4d63854c33967d1646b5e89a9a19a2"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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