CVE-2024-35814

CVE Details

Release Date:

2024-05-17

Description

In the Linux kernel, the following vulnerability has been resolved:\nswiotlb: Fix double-allocation of slots due to broken alignment handling\nCommit bbb73a103fbb ('swiotlb: fix a braino in the alignment check fix'),\nwhich was a fix for commit 0eee5ae10256 ('swiotlb: fix slot alignment\nchecks'), causes a functional regression with vsock in a virtual machine\nusing bouncing via a restricted DMA SWIOTLB pool.\nWhen virtio allocates the virtqueues for the vsock device using\ndma_alloc_coherent(), the SWIOTLB search can return page-unaligned\nallocations if 'area->index' was left unaligned by a previous allocation\nfrom the buffer:\n# Final address in brackets is the SWIOTLB address returned to the caller\n| virtio-pci 0000:00:07.0: orig_addr 0x0 alloc_size 0x2000, iotlb_align_mask 0x800 stride 0x2: got slot 1645-1649/7168 (0x98326800)\n| virtio-pci 0000:00:07.0: orig_addr 0x0 alloc_size 0x2000, iotlb_align_mask 0x800 stride 0x2: got slot 1649-1653/7168 (0x98328800)\n| virtio-pci 0000:00:07.0: orig_addr 0x0 alloc_size 0x2000, iotlb_align_mask 0x800 stride 0x2: got slot 1653-1657/7168 (0x9832a800)\nThis ends badly (typically buffer corruption and/or a hang) because\nswiotlb_alloc() is expecting a page-aligned allocation and so blindly\nreturns a pointer to the 'struct page' corresponding to the allocation,\ntherefore double-allocating the first half (2KiB slot) of the 4KiB page.\nFix the problem by treating the allocation alignment separately to any\nadditional alignment requirements from the device, using the maximum\nof the two as the stride to search the buffer slots and taking care\nto ensure a minimum of page-alignment for buffers larger than a page.\nThis also resolves swiotlb allocation failures occuring due to the\ninclusion of ~PAGE_MASK in 'iotlb_align_mask' for large allocations and\nresulting in alignment requirements exceeding swiotlb_max_mapping_size().

See more information about CVE-2024-35814 from MITRE CVE dictionary and NIST NVD

CVSS Scoring

NOTE: The following CVSS v3.1 metrics and score provided are preliminary and subject to review.

Base Score:	5.5	CVSS Vector:	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector:	Local network	Attack Complexity:	Low
Privileges Required:	Low	User Interaction:	None
Scope:	Unchanged	Confidentiality Impact:	None
Integrity Impact:	None	Availability Impact:	High

Errata information

Platform	Errata	Release Date
Oracle Linux version 8 (kernel)	ELSA-2024-5101	2024-08-08
Oracle Linux version 9 (kernel)	ELSA-2024-9315	2024-11-14