CVE-2023-53254

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.