CVE-2026-80633

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

iommufd: Take dma_resv lock before dma_buf_unpin() in release path

dma_buf_unpin() requires the caller to hold the exporter's dma_resv

lock:

void dma_buf_unpin(struct dma_buf_attachment *attach)

{

...

dma_resv_assert_held(dmabuf->resv);

...

}

iopt_release_pages() calls dma_buf_unpin() without taking that lock,

so every iommufd_ioas_destroy()/iommufd_ioas_unmap() that releases

the last reference on a DMABUF-backed iopt_pages triggers a WARN.

This was hit while running tools/testing/selftests/iommu/iommufd:

WARNING: drivers/dma-buf/dma-buf.c:1137 at dma_buf_unpin+0x62/0x70

RIP: 0010:dma_buf_unpin+0x62/0x70

Call Trace:

<TASK>

dma_buf_unpin+0x62/0x70

iopt_release_pages+0xe4/0x190

iopt_unmap_iova_range+0x1c7/0x290

iopt_unmap_all+0x1a/0x30

iommufd_ioas_destroy+0x1d/0x50

iommufd_fops_release+0x93/0x150

__fput+0xfc/0x2c0

__x64_sys_close+0x3d/0x80

do_s

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References