CVE-2024-46689

/// Technical description

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

soc: qcom: cmd-db: Map shared memory as WC, not WB

Linux does not write into cmd-db region. This region of memory is write

protected by XPU. XPU may sometime falsely detect clean cache eviction

as "write" into the write protected region leading to secure interrupt

which causes an endless loop somewhere in Trust Zone.

The only reason it is working right now is because Qualcomm Hypervisor

maps the same region as Non-Cacheable memory in Stage 2 translation

tables. The issue manifests if we want to use another hypervisor (like

Xen or KVM), which does not know anything about those specific mappings.

Changing the mapping of cmd-db memory from MEMREMAP_WB to MEMREMAP_WT/WC

removes dependency on correct mappings in Stage 2 tables. This patch

fixes the issue by updating the mapping to MEMREMAP_WC.

I tested this on SA8155P with Xen.

/// 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