CVE-2024-36911 in Linux
Summary
by MITRE • 05/30/2024
In the Linux kernel, the following vulnerability has been resolved:
hv_netvsc: Don't free decrypted memory
In CoCo VMs it is possible for the untrusted host to cause set_memory_encrypted() or set_memory_decrypted() to fail such that an error is returned and the resulting memory is shared. Callers need to take care to handle these errors to avoid returning decrypted (shared) memory to the page allocator, which could lead to functional or security issues.
The netvsc driver could free decrypted/shared pages if set_memory_decrypted() fails. Check the decrypted field in the gpadl to decide whether to free the memory.
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Analysis
by VulDB Data Team • 09/30/2025
The vulnerability described in CVE-2024-36911 resides within the Linux kernel's hv_netvsc driver component, which manages network virtualization for Hyper-V environments. This flaw specifically impacts CoCo (Confidential Computing) virtual machines where the host system operates in a potentially untrusted state. The issue manifests when memory encryption and decryption operations fail during the network virtualization process, creating a scenario where memory pages that should remain encrypted become accessible to the guest operating system. The root cause stems from improper error handling in the memory management routines that govern how decrypted memory pages are managed within the virtualized network interface driver.
The technical implementation flaw occurs when the set_memory_decrypted() function fails to properly decrypt memory pages in CoCo VMs, resulting in an error return code while the memory remains in a shared state. The hv_netvsc driver fails to properly check the decrypted field within the GPADL (Guest Physical Address Descriptor List) structure before proceeding with memory deallocation. This oversight allows the driver to free memory pages that have not been successfully decrypted, potentially exposing sensitive data or creating functional inconsistencies. The vulnerability specifically affects the memory management logic where the driver assumes successful decryption and proceeds with freeing operations without verifying the actual state of the memory pages. This represents a classic case of improper error handling in kernel space memory management, where error conditions are not properly accounted for in the cleanup routines.
The operational impact of this vulnerability extends beyond simple memory management issues to encompass potential security implications within confidential computing environments. When the driver frees decrypted or shared memory pages, it creates opportunities for information leakage or privilege escalation attacks that could compromise the integrity of CoCo VMs. The vulnerability allows an untrusted host to potentially manipulate memory states in ways that could expose sensitive data to unauthorized access or disrupt normal system operations. In production environments utilizing Hyper-V with confidential computing workloads, this flaw could enable adversaries to gain insights into memory contents or manipulate network packet processing, potentially leading to data exfiltration or system compromise. The issue particularly affects systems where memory encryption is actively used to protect sensitive data, making it a significant concern for enterprise security infrastructure.
Mitigation strategies for CVE-2024-36911 require immediate patch application to the Linux kernel, specifically targeting the hv_netvsc driver implementation. System administrators should prioritize updating their kernel versions to include the fix that properly validates the decrypted field in GPADL structures before memory deallocation occurs. The recommended approach involves verifying that all memory management operations in the network virtualization layer properly handle error conditions from encryption and decryption functions, ensuring that memory pages are only freed when their state is definitively known. Organizations should implement monitoring for memory allocation patterns and error logs related to hv_netvsc operations to detect potential exploitation attempts. The fix aligns with security best practices outlined in CWE-394 and addresses ATT&CK techniques related to privilege escalation and information disclosure. Additionally, system administrators should review their Hyper-V configuration settings to ensure proper memory encryption policies are enforced and consider implementing additional security controls around virtual machine memory management to prevent similar vulnerabilities in other kernel components.