CVE-2026-93233 (GCVE-0-2026-93233)

Vulnerability from cvelistv5 – Published: 2026-09-24 15:32 – Updated: 2026-10-19 09:07
VLAI
Title
drm/nouveau/dmem: fix callocated underflow on large folio split
Summary
In the Linux kernel, the following vulnerability has been resolved: drm/nouveau/dmem: fix callocated underflow on large folio split nouveau_dmem_folio_free() drops chunk->callocated once per freed folio, while a large (compound) device-private folio is only counted once when it is allocated. When such a folio is split, the mm core invokes ->folio_split() (nouveau_dmem_folio_split()) once for each new sub-folio, but the hook only fixes up the sub-folio metadata and leaves chunk->callocated unchanged. Each resulting sub-folio is later freed separately, so after a split the single allocation (+1) is met by N frees (-N), leaving chunk->callocated short by N-1. On the first split/free cycle it underflows: WARN_ON(!chunk->callocated) fires, the unsigned counter wraps and never returns to zero, so the chunk can no longer be reclaimed (nouveau_dmem_fini() also warns on the leaked count). Account for the new sub-folio in the split hook, under the same lock as nouveau_dmem_folio_free(), so the count stays balanced.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6641 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: c3228747107705d47c7e9a03598a434a0380cb73 , < 0163b92946d0a7c816f619c57a4d9867954dd106 (git)
Affected: c3228747107705d47c7e9a03598a434a0380cb73 , < c2256c044a1df39c8aad4dd2d6f709b2533e2d7a (git)
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Linux Linux Affected: 6.19
Unaffected: 0 , < 6.19 (semver)
Unaffected: 7.2.5 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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{
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          "programFiles": [
            "drivers/gpu/drm/nouveau/nouveau_dmem.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/nouveau/dmem: fix callocated underflow on large folio split\n\nnouveau_dmem_folio_free() drops chunk-\u003ecallocated once per freed folio,\nwhile a large (compound) device-private folio is only counted once when\nit is allocated.  When such a folio is split, the mm core invokes\n-\u003efolio_split() (nouveau_dmem_folio_split()) once for each new\nsub-folio, but the hook only fixes up the sub-folio metadata and leaves\nchunk-\u003ecallocated unchanged.\n\nEach resulting sub-folio is later freed separately, so after a split\nthe single allocation (+1) is met by N frees (-N), leaving\nchunk-\u003ecallocated short by N-1.  On the first split/free cycle it\nunderflows: WARN_ON(!chunk-\u003ecallocated) fires, the unsigned counter\nwraps and never returns to zero, so the chunk can no longer be\nreclaimed (nouveau_dmem_fini() also warns on the leaked count).\n\nAccount for the new sub-folio in the split hook, under the same lock as\nnouveau_dmem_folio_free(), so the count stays balanced."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:07:44.949Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/0163b92946d0a7c816f619c57a4d9867954dd106"
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          "url": "https://git.kernel.org/stable/c/c2256c044a1df39c8aad4dd2d6f709b2533e2d7a"
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      ],
      "title": "drm/nouveau/dmem: fix callocated underflow on large folio split",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-93233",
    "datePublished": "2026-09-24T15:32:51.743Z",
    "dateReserved": "2026-09-17T16:02:15.095Z",
    "dateUpdated": "2026-10-19T09:07:44.949Z",
    "state": "PUBLISHED"
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        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/nouveau/dmem: fix callocated underflow on large folio split\n\nnouveau_dmem_folio_free() drops chunk-\u003ecallocated once per freed folio,\nwhile a large (compound) device-private folio is only counted once when\nit is allocated.  When such a folio is split, the mm core invokes\n-\u003efolio_split() (nouveau_dmem_folio_split()) once for each new\nsub-folio, but the hook only fixes up the sub-folio metadata and leaves\nchunk-\u003ecallocated unchanged.\n\nEach resulting sub-folio is later freed separately, so after a split\nthe single allocation (+1) is met by N frees (-N), leaving\nchunk-\u003ecallocated short by N-1.  On the first split/free cycle it\nunderflows: WARN_ON(!chunk-\u003ecallocated) fires, the unsigned counter\nwraps and never returns to zero, so the chunk can no longer be\nreclaimed (nouveau_dmem_fini() also warns on the leaked count).\n\nAccount for the new sub-folio in the split hook, under the same lock as\nnouveau_dmem_folio_free(), so the count stays balanced."
          }
        ],
        "id": "CVE-2026-93233",
        "lastModified": "2026-10-19T10:17:14.360",
        "metrics": {},
        "published": "2026-09-24T16:17:18.887",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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      "current_release_date": "2026-11-11T19:17:44+00:00",
      "cve": "CVE-2026-93233",
      "id": "CVE-2026-93233",
      "initial_release_date": "2026-09-24T00:00:00+00:00",
      "product_status:known_not_affected": "203",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: drm/nouveau/dmem: fix callocated underflow on large folio split",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-93233.json",
      "version": "3"
    }
  }
}



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