Memory Corruption in Linux Kernel's Identity Domain for s390 Devices

CVE-2025-39939

What is CVE-2025-39939?

A vulnerability in the Linux kernel impacts devices using the identity domain within the s390 architecture. Specifically, when calling the function zpci_get_iommu_ctrs(), the kernel attempts to access counter information related to device statistics stored in the s390_domain. However, the identity domain is not associated with a legitimate s390_domain, resulting in a bad address being referenced. This flaw can lead to memory corruption, revealed by KASAN reports indicating global-out-of-bounds errors when devices in the identity domain are accessed. The system's handling of counters for the identity domain could result in instability and security threats, prompting a necessary fix to return NULL instead of erroneous data.

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