CVE-2024-35814

high

Published 2024-11-12 · Modified 2024-08-08

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CVSS v3

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CVSS v4 NEW

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not yet in upstream

VIR risk

8.0

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: 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().

Predictions

Exploit likelihood

20%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

Mitigation details

Source: Red Hat Errata — Red Hat Inc. · View original ↗ · Open-Errata-API

Description kernel: swiotlb: Fix double-allocation of slots due to broken alignment handling CVSS v3: 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) Errata / fixed releases ProductPackageAdvisoryReleased Red Hat Enterprise Linux 8kernel-rt-0:4.18.0-553.16.1.rt7.357.el8_10RHSA-2024:51022024-08-08T00:00:00Z Red Hat Enterprise Linux…

Description

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

CVSS v3: 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)

Errata / fixed releases

Product	Package	Advisory	Released
Red Hat Enterprise Linux 8	`kernel-rt-0:4.18.0-553.16.1.rt7.357.el8_10`	RHSA-2024:5102	2024-08-08T00:00:00Z
Red Hat Enterprise Linux 8	`kernel-0:4.18.0-553.16.1.el8_10`	RHSA-2024:5101	2024-08-08T00:00:00Z
Red Hat Enterprise Linux 9	`kernel-0:5.14.0-503.11.1.el9_5`	RHSA-2024:9315	2024-11-12T00:00:00Z
Red Hat Enterprise Linux 9	`kernel-0:5.14.0-503.11.1.el9_5`	RHSA-2024:9315	2024-11-12T00:00:00Z
Red Hat Enterprise Linux 9.4 Extended Update Support	`kernel-0:5.14.0-427.44.1.el9_4`	RHSA-2024:9546	2024-11-13T00:00:00Z

Package state

Product	Package	State
Red Hat Enterprise Linux 6	`kernel`	Not affected
Red Hat Enterprise Linux 7	`kernel`	Not affected
Red Hat Enterprise Linux 7	`kernel-rt`	Not affected
Red Hat Enterprise Linux 9	`kernel-rt`	Affected

Apply commands

bash fix

Apply RHSA-2024:5102 for Red Hat Enterprise Linux 8

yum update -y kernel-rt
# or:
dnf upgrade -y kernel-rt

Affected

Vendor	Product	Version
redhat	Red Hat Enterprise Linux 6	`Not affected`
redhat	Red Hat Enterprise Linux 7	`Not affected`
redhat	Red Hat Enterprise Linux 7	`Not affected`
redhat	Red Hat Enterprise Linux 9	`Affected`

OS impact

SUSE Affected 1 release

Version	Status	Fixed in
—	Affected	—

AlmaLinux Fixed 1 release

Version	Status	Fixed in
8	Fixed	`kernel-doc-4.18.0-553.16.1.el8_10.noarch.rpm`

Debian Fixed 5 releases

Version	Status	Fixed in
trixie	Fixed	`6.7.12-1`
sid	Fixed	`6.7.12-1`
forky	Fixed	`6.7.12-1`
bullseye	Fixed	`0`
bookworm	Fixed	`0`

Red Hat Fixed 2 releases

Version	Status	Fixed in
9	Fixed	—
8	Fixed	—

Rocky Linux Fixed 1 release

Version	Status	Fixed in
8	Fixed	—

References

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.