CVE-2023-53996

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

x86/sev: Make enc_dec_hypercall() accept a size instead of npages

enc_dec_hypercall() accepted a page count instead of a size, which forced its callers to round up. As a result, non-page aligned vaddrs caused pages to be spuriously marked as decrypted via the encryption status hypercall, which in turn caused consistent corruption of pages during live migration. Live migration requires accurate encryption status information to avoid migrating pages from the wrong perspective.

This vulnerability is rated as having a Moderate severity because it requires specific virtualization hardware features and occurs only under specific operational conditions during guest live migration, limiting its general blast radius. The issue affects systems utilizing AMD Secure Encrypted Virtualization (SEV) when migrating virtual machines with unaligned virtual memory addresses, potentially resulting in guest memory corruption and loss of availability. Systems running standard virtual machines without AMD SEV enabled or workloads that do not undergo live migration remain unaffected.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.