CVE-2024-36912

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

Drivers: hv: vmbus: Track decrypted status in vmbus_gpadl

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.

In order to make sure callers of vmbus_establish_gpadl() and vmbus_teardown_gpadl() dont return decrypted/shared pages to allocators, add a field in struct vmbus_gpadl to keep track of the decryption status of the buffers. This will allow the callers to know if they should free or leak the pages.

Weakness

The hardware does not fully clear security-sensitive values, such as keys and intermediate values in cryptographic operations, when debug mode is entered.

Affected Software

Extended Description

Security sensitive values, keys, intermediate steps of cryptographic operations, etc. are stored in temporary registers in the hardware. If these values are not cleared when debug mode is entered they may be accessed by a debugger allowing sensitive information to be accessible by untrusted parties.

Potential Mitigations

• Whenever debug mode is enabled, all registers containing sensitive assets must be cleared.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/150.html
• https://cwe.mitre.org/data/definitions/204.html
• https://cwe.mitre.org/data/definitions/37.html
• https://cwe.mitre.org/data/definitions/545.html

References

• https://git.kernel.org/stable/c/1999644d95194d4a58d3e80ad04ce19220a01a81
• https://git.kernel.org/stable/c/211f514ebf1ef5de37b1cf6df9d28a56cfd242ca
• https://git.kernel.org/stable/c/8e62341f5c45b27519b7d193bcc32ada416ad9d8
• https://git.kernel.org/stable/c/bfae56be077ba14311509e70706a13458f87ea99