CVE-2026-93233
Received
Received - Intake
Integer Underflow in Nouveau DRM Kernel Module
Vulnerability report for CVE-2026-93233, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-09-24
Last updated on: 2026-09-24
Assigner: kernel.org
Description
Description
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.
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | kernel | * |
| nouveau | linux_kernel | * |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
