CVE-2026-89804 drm/nouveau/dmem: fix mismatched DMA unmap size for large folios
A mismatched DMA unmap size in the nouveau driver leaks IOMMU mappings for large folios, potentially causing resource exhaustion or instability.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89804?
CVE-2026-89804 is a high-severity memory corruption vulnerability in Linux, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
drm/nouveau/dmem: fix mismatched DMA unmap size for large folios
Device-private THP migration maps migration buffers with page_size() and records that length in dma_info->size. For a compound folio page_size() is PAGE_SIZE << order, but two teardown sites still pass a literal PAGE_SIZE to dma_unmap_page():
- nouveau_dmem_migrate_to_ram() on the success path, and - nouveau_dmem_migrate_copy_one() on the copy-error path.
For an order > 0 folio this unmaps less than was mapped, leaking the remainder of the IOMMU/IOVA mapping. The other unmap sites, in nouveau_dmem_migrate_chunk() and nouveau_dmem_evict_chunk(), already use the saved size; use it here too.
Which versions are affected by CVE-2026-89804?
How do I fix CVE-2026-89804?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-89804 being exploited?
There is no known exploitation of CVE-2026-89804 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-89804, GHSA-f67x-82w6-7jjx, UBUNTU-CVE-2026-89804.