CVE-2023-53254: Out-of-bounds Read

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

cacheinfo: Fix shared_cpu_map to handle shared caches at different levels

The cacheinfo sets up the shared_cpu_map by checking whether the caches with the same index are shared between CPUs. However, this will trigger slab-out-of-bounds access if the CPUs do not have the same cache hierarchy. Another problem is the mismatched shared_cpu_map when the shared cache does not have the same index between CPUs.

CPU0 I D L3 index 0 1 2 x ^ ^ ^ ^ index 0 1 2 3 CPU1 I D L2 L3

This patch checks each cache is shared with all caches on other CPUs.