CVE-2023-52455

/// Technical description

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

iommu: Don't reserve 0-length IOVA region

When the bootloader/firmware doesn't setup the framebuffers, their

address and size are 0 in "iommu-addresses" property. If IOVA region is

reserved with 0 length, then it ends up corrupting the IOVA rbtree with

an entry which has pfn_hi < pfn_lo.

If we intend to use display driver in kernel without framebuffer then

it's causing the display IOMMU mappings to fail as entire valid IOVA

space is reserved when address and length are passed as 0.

An ideal solution would be firmware removing the "iommu-addresses"

property and corresponding "memory-region" if display is not present.

But the kernel should be able to handle this by checking for size of

IOVA region and skipping the IOVA reservation if size is 0. Also, add

a warning if firmware is requesting 0-length IOVA region reservation.

/// 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