ghsa-rqvp-j9p2-fcwx
Vulnerability from github
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: orig_addr 0x0 alloc_size 0x2000, iotlb_align_mask 0x800 stride 0x2: got slot 1653-1657/7168 (0x9832a800)
This ends badly (typically buffer corruption and/or a hang) because swiotlb_alloc() is expecting a page-aligned allocation and so blindly returns a pointer to the 'struct page' corresponding to the allocation, therefore double-allocating the first half (2KiB slot) of the 4KiB page.
Fix the problem by treating the allocation alignment separately to any additional alignment requirements from the device, using the maximum of the two as the stride to search the buffer slots and taking care to ensure a minimum of page-alignment for buffers larger than a page.
This also resolves swiotlb allocation failures occuring due to the inclusion of ~PAGE_MASK in 'iotlb_align_mask' for large allocations and resulting in alignment requirements exceeding swiotlb_max_mapping_size().
{
"affected": [],
"aliases": [
"CVE-2024-35814"
],
"database_specific": {
"cwe_ids": [
"CWE-1055"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-17T14:15:15Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nswiotlb: Fix double-allocation of slots due to broken alignment handling\n\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.\n\nWhen virtio allocates the virtqueues for the vsock device using\ndma_alloc_coherent(), the SWIOTLB search can return page-unaligned\nallocations if \u0027area-\u003eindex\u0027 was left unaligned by a previous allocation\nfrom the buffer:\n\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)\n\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 \u0027struct page\u0027 corresponding to the allocation,\ntherefore double-allocating the first half (2KiB slot) of the 4KiB page.\n\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.\n\nThis also resolves swiotlb allocation failures occuring due to the\ninclusion of ~PAGE_MASK in \u0027iotlb_align_mask\u0027 for large allocations and\nresulting in alignment requirements exceeding swiotlb_max_mapping_size().",
"id": "GHSA-rqvp-j9p2-fcwx",
"modified": "2024-07-03T18:42:25Z",
"published": "2024-05-17T15:31:10Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-35814"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/04867a7a33324c9c562ee7949dbcaab7aaad1fb4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3e7acd6e25ba77dde48c3b721c54c89cd6a10534"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/777391743771040e12cc40d3d0d178f70c616491"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c88668aa6c1da240ea3eb4d128b7906e740d3cb8"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
"type": "CVSS_V3"
}
]
}
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.