drm/virtio: use the DMA API for resource backing on Xen
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 6.6.160, 6.12.114, 6.18.53, 7.2.7
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
In the Linux kernel, the following vulnerability has been resolved: drm/virtio: use the DMA API for resource backing on Xen On a Xen PV domain page addresses bear no relation to the real machine addresses the host would have to use to reach it. virtio_ring.c handles this correctly, vring_use_map_api() returns true for any xen_domain() regardless of VIRTIO_F_ACCESS_PLATFORM. virtio-gpu makes the same decision independently, but its copy looks only at the feature bit: bool use_dma_api = !virtio_has_dma_quirk(vgdev->vdev); QEMU does not set iommu_platform on virtio-vga by default, so VIRTIO_F_ACCESS_PLATFORM is not negotiated, use_dma_api is false, and virtio_gpu_object_shmem_init() describes the framebuffer's backing pages to the host with sg_phys(). Those are guest-physical addresses. In a PV domain they resolve, on the host side, to pages belonging to some other domain, so the host scans out unrelated memory. Move the decision into virtio_gpu_use_dma_api() and give it the xen_domain() check, like vring_use_map_api() has. This additionally enables the dma_sync_sgtable_for_device() calls in virtgpu_vq.c, which are required for correctness whenever swiotlb is in play. Reproduced with a Xen 4.21 PV dom0 nested inside QEMU 8.2 with virtio-vga, on both a distro 6.8 kernel and 6.18 LTS. A PVH dom0 works fine and doesn't need this fix because it is identity-mapped, only PV dom0s are affected.
Timeline
- CVE published
- Record last updated
Affected versions
- Linux Linux
From a3b815f09bb846255c458c181b8a5b1cc66891b4 · fixed in 32e999ccf5f6453b3b4df8264ff1b03c6720292f; From a3b815f09bb846255c458c181b8a5b1cc66891b4 · fixed in 3f130cc6826fabf50e01fe8e4ff3ed1fcae50d36; From a3b815f09bb846255c458c181b8a5b1cc66891b4 · fixed in 93c557e947ef0040004b1ac6a1c1265d79a957e1; From a3b815f09bb846255c458c181b8a5b1cc66891b4 · fixed in 455184dbe9652d01470d3c5cf5edd09a7a673a99; From a3b815f09bb846255c458c181b8a5b1cc66891b4 · fixed in 6a736d2f9d0c6e6217fe7532bc4c50ceca71db78
- Linux Linux
4.20
- KernelLinux
From 4.20.0 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.114; From 6.13.0 · fixed in 6.18.53; From 6.19.0 · fixed in 7.2.7