CVE-2024-56669 Information

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: ? __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.

Reference

https://git.kernel.org/stable/c/1f2557e08a617a4b5e92a48a1a9a6f86621def18 https://git.kernel.org/stable/c/9a0a72d3ed919ebe6491f527630998be053151d8