CVE-2022-49556 is a vulnerability identified in the Linux kernel's implementation of Kernel-based Virtual Machine (KVM) Secure Encrypted Virtualization (SEV) Secure Virtual Machine (SVM) ioctl interfaces. The issue arises from improper memory allocation when handling certain SEV ioctl calls. Specifically, the length parameter passed to these interfaces may be less than or equal to SEV_FW_BLOB_MAX_SIZE but larger than the actual data size returned by the Platform Security Processor (PSP) firmware. The kernel uses kmalloc to allocate memory based on the input length rather than the actual data size. Since the PSP firmware does not fully overwrite the allocated buffer, this results in the ioctl interface potentially returning uninitialized kernel slab memory. This uninitialized memory could contain sensitive kernel data, leading to an information leak. The vulnerability is rooted in the use of kmalloc instead of kzalloc, which would zero-initialize the allocated memory and prevent leakage of residual data. The flaw affects multiple versions of the Linux kernel as indicated by the repeated affected version hashes. No known exploits are reported in the wild as of the publication date. The vulnerability impacts confidentiality by potentially exposing kernel memory contents to user space through SEV ioctl interfaces, which are typically used in virtualized environments leveraging AMD SEV technology for VM encryption. The vulnerability does not appear to require elevated privileges beyond those needed to invoke the SEV ioctl interfaces, which are generally restricted to privileged users or processes managing virtual machines. No CVSS score is assigned yet, and no patches or mitigations are linked in the provided data, though the description notes that the issue has been resolved by switching to kzalloc for memory allocation in the affected code paths.

For European organizations, the impact of CVE-2022-49556 can be significant, particularly for those relying on Linux-based virtualization infrastructure using AMD SEV technology. The vulnerability could allow an attacker with access to SEV ioctl interfaces to leak sensitive kernel memory contents, potentially exposing cryptographic keys, credentials, or other confidential information residing in kernel memory. This could undermine the confidentiality guarantees of virtual machines protected by SEV encryption, impacting cloud service providers, data centers, and enterprises using Linux virtualization for critical workloads. The information leak could facilitate further attacks such as privilege escalation or VM escape if combined with other vulnerabilities. Organizations in sectors with strict data protection requirements, such as finance, healthcare, and government, may face compliance risks if sensitive data is exposed. While exploitation requires access to privileged interfaces, insider threats or compromised management systems could leverage this vulnerability. The lack of known exploits in the wild reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits once patches are widely deployed.

To mitigate CVE-2022-49556, European organizations should: 1) Apply the latest Linux kernel updates that include the fix switching from kmalloc to kzalloc for SEV ioctl memory allocations, ensuring zero-initialization of buffers to prevent data leakage. 2) Restrict access to SEV ioctl interfaces strictly to trusted and authenticated administrative users or processes, minimizing the attack surface. 3) Implement rigorous monitoring and auditing of virtualization management activities to detect anomalous or unauthorized ioctl calls. 4) Employ kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR) and secure boot to reduce the risk of kernel memory disclosure. 5) For environments using AMD SEV, verify firmware and platform security processor updates are current to complement kernel mitigations. 6) Conduct regular security assessments and penetration testing focused on virtualization components to identify potential exploitation attempts. 7) Maintain strict separation of duties and least privilege principles for users managing virtual machines and kernel interfaces. These targeted measures go beyond generic advice by focusing on the specific interfaces and conditions involved in this vulnerability.