{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2025-37908",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2025-37908"
  ],
  "published": "2025-05-20T15:22:31Z",
  "summary": "mm, slab: clean up slab->obj_exts always",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm, slab: clean up slab->obj_exts always\n\nWhen memory allocation profiling is disabled at runtime or due to an\nerror, shutdown_mem_profiling() is called: slab->obj_exts which\npreviously allocated remains.\nIt won't be cleared by unaccount_slab() because of\nmem_alloc_profiling_enabled() not true. It's incorrect, slab->obj_exts\nshould always be cleaned up in unaccount_slab() to avoid following error:\n\n[...]BUG: Bad page state in process...\n..\n[...]page dumped because: page still charged to cgroup\n\n[andriy.shevchenko@linux.intel.com: fold need_slab_obj_ext() into its only user]",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
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  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-37908"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/dab2a13059a475b6392550f882276e170fe2fcff"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/01db0e1a48345aa1937f3bdfc7c7108d03ebcf7e"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/be8250786ca94952a19ce87f98ad9906448bc9ef"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T12:19:11Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The vulnerable code is `unaccount_slab()` in core mm/slub, reached whenever a slab page is destroyed; an attacker must be on the system to drive slab allocation/destruction churn (file/socket/dentry creation plus memory pressure). There is no network protocol handler involved, so this is local.\nAC:L - Once memory allocation profiling has been shut down (sysctl toggle, or automatically via `shutdown_mem_profiling()` on a module-load tag-budget failure), every subsequent slab destruction deterministically leaks `obj_exts` and leaves a stale `page->memcg_data` \u2014 no race, no timing, and the attacker reliably forces slab teardown at will.\nPR:L - No privileges are needed for the trigger itself \u2014 any unprivileged local user can allocate and free enough objects to force `__free_slab()` \u2192 `unaccount_slab()` repeatedly. The precondition of profiling being disabled is pre-existing system state, not something the attacker must have rights to set.\nUI:N - The leak and the stale `memcg_data` are produced entirely by the attacker's own allocation/free activity in kernel context. No victim action of any kind is required.\nS:U - The leaked vector, the corrupted `page->memcg_data`, and any resulting corruption all stay within the kernel's own security authority. No hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - The `bad_page()` report emits the raw `slabobj_ext` heap pointer (`memcg:%lx`) plus a full hex dump of `struct page` into the kernel log, and when page checks are off the stale pointer is type-confused as a `struct mem_cgroup *` by `__folio_memcg()`, giving wild-pointer reads inside memcg accounting \u2014 memory corruption leverageable for disclosure.\nI:H - Slab folios re-enter the buddy allocator carrying a bogus `struct mem_cgroup *`, and `split_page_memcg()` propagates it to tail pages and calls `css_get_many()` through it, writing via a percpu refcount pointer read out of the attacker-groomable `slabobj_ext` array \u2014 a type-confusion write primitive.\nA:H - Every destroyed slab leaks its `obj_exts` vector, and with page sanity checks enabled `free_pages_prepare()` returns false so the entire slab folio is permanently leaked as well while the kernel is tainted \u2014 sustained slab churn drives unbounded memory exhaustion and OOM, on top of the crashes from the stale-pointer/`VM_BUG_ON_FOLIO` paths."
    }
  }
}