CVE-2024-56669: iommu/vt-d: Remove cache tags before disabling ATS

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-12-27 · updated 2026-08-04
Weakness: CWE-401

Description

In the Linux kernel, the following vulnerability has been resolved: iommu/vt-d: Remove cache tags before disabling ATS The current implementation removes cache tags after disabling ATS, leading to potential memory leaks and kernel crashes. Specifically, CACHE_TAG_DEVTLB type cache tags may still remain in the list even after the domain is freed, causing a use-after-free condition. This issue really shows up when multiple VFs from different PFs passed through to a single user-space process via vfio-pci. In such cases, the kernel may crash with kernel messages like: BUG: kernel NULL pointer dereference, address: 0000000000000014 PGD 19036a067 P4D 1940a3067 PUD 136c9b067 PMD 0 Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 74 UID: 0 PID: 3183 Comm: testCli Not tainted 6.11.9 #2 RIP: 0010:cache_tag_flush_range+0x9b/0x250 Call Trace: <TASK> ? __die+0x1f/0x60 ? page_fault_oops+0x163/0x590 ? exc_page_fault+0x72/0x190 ? asm_exc_page_fault+0x22/0x30 ? cache_tag_flush_range+0x9b/0x250 ? cache_tag_flush_range+0x5d/0x250 intel_iommu_tlb_sync+0x29/0x40 intel_iommu_unmap_pages+0xfe/0x160 __iommu_unmap+0xd8/0x1a0 vfio_unmap_unpin+0x182/0x340 [vfio_iommu_type1] vfio_remove_dma+0x2a/0xb0 [vfio_iommu_type1] vfio_iommu_type1_ioctl+0xafa/0x18e0 [vfio_iommu_type1] Move cache_tag_unassign_domain() before iommu_disable_pci_caps() to fix it.

Affected products

Linux kernel: from 6.10 before 6.12.6; 6.13-rc1, 6.13-rc2 — fixed in 6.12.6

How to fix

Upgrade to a fixed version: Linux kernel 6.12.6. Check the vendor advisory for mitigations.

References

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