Bug 2395386 (CVE-2023-53254)

Summary: CVE-2023-53254 kernel: cacheinfo: Fix shared_cpu_map to handle shared caches at different levels
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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Description OSIDB Bzimport 2025-09-15 15:10:59 UTC 
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.
Comment 1 Jon Moroney 2025-09-15 18:43:05 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025091503-CVE-2023-53254-0aa0@gregkh/T