CVE-2026-89804 — drm/nouveau/dmem: fix mismatched DMA unmap size for large folios

Affected: Linux

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.

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CVE-2026-89804 — drm/nouveau/dmem: fix mismatched DMA unmap size for large folios