Vulnerability CVE-2024-46689
Published: 2024-09-13

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.

 References:
https://git.kernel.org/stable/c/0ee9594c974368a17e85a431e9fe1c14fb65c278
https://git.kernel.org/stable/c/f5a5a5a0e95f36e2792d48e6e4b64e665eb01374
https://git.kernel.org/stable/c/eaff392c1e34fb77cc61505a31b0191e5e46e271
https://git.kernel.org/stable/c/d9d48d70e922b272875cda60d2ada89291c840cf
https://git.kernel.org/stable/c/ef80520be0ff78ae5ed44cb6eee1525e65bebe70
https://git.kernel.org/stable/c/62c2d63605ca25b5db78a347ed303c0a0a77d5b4
https://git.kernel.org/stable/c/f9bb896eab221618927ae6a2f1d566567999839d
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