CVE-2024-35814

/// Technical description

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

swiotlb: Fix double-allocation of slots due to broken alignment handling

Commit bbb73a103fbb ("swiotlb: fix a braino in the alignment check fix"),

which was a fix for commit 0eee5ae10256 ("swiotlb: fix slot alignment

checks"), causes a functional regression with vsock in a virtual machine

using bouncing via a restricted DMA SWIOTLB pool.

When virtio allocates the virtqueues for the vsock device using

dma_alloc_coherent(), the SWIOTLB search can return page-unaligned

allocations if 'area->index' was left unaligned by a previous allocation

from the buffer:

# Final address in brackets is the SWIOTLB address returned to the caller

| virtio-pci 0000:00:07.0: orig_addr 0x0 alloc_size 0x2000, iotlb_align_mask 0x800 stride 0x2: got slot 1645-1649/7168 (0x98326800)

| virtio-pci 0000:00:07.0: orig_addr 0x0 alloc_size 0x2000, iotlb_align_mask 0x800 stride 0x2: got slot 1649-1653/7168 (0x98328800)

| virtio-pci 0000:00:07.0

/// 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