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

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/4deb29b9d33bfdb3de4d2d9944947ecf77221e42
• https://git.kernel.org/stable/c/caa1bc2a0a6ca19dcb90bbf88208b0fe2decd66f