Vulnerability CVE-2024-36909
Published: 2024-05-30

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

Drivers: hv: vmbus: Don't free ring buffers that couldn't be re-encrypted

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 VMBus ring buffer code could free decrypted/shared pages if
set_memory_decrypted() fails. Check the decrypted field in the struct
vmbus_gpadl for the ring buffers to decide whether to free the memory.

 References:
https://git.kernel.org/stable/c/2f622008bf784a9f5dd17baa19223cc2ac30a039
https://git.kernel.org/stable/c/82f9e213b124a7d2bb5b16ea35d570260ef467e0
https://git.kernel.org/stable/c/a9212a4e2963a7fbe3864ba33dc551d4ad8d0abb
https://git.kernel.org/stable/c/30d18df6567be09c1433e81993e35e3da573ac48
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