Subject: CVE-2024-36912: Drivers: hv: vmbus: Track decrypted status in vmbus_gpadl

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

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() don't 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.

The Linux kernel CVE team has assigned CVE-2024-36912 to this issue.

Affected and fixed versions
===========================

	Fixed in 6.1.91 with commit 1999644d9519
	Fixed in 6.6.31 with commit 8e62341f5c45
	Fixed in 6.8.10 with commit bfae56be077b
	Fixed in 6.9 with commit 211f514ebf1e

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-36912
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/hv/channel.c
	include/linux/hyperv.h

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/1999644d95194d4a58d3e80ad04ce19220a01a81
	https://git.kernel.org/stable/c/8e62341f5c45b27519b7d193bcc32ada416ad9d8
	https://git.kernel.org/stable/c/bfae56be077ba14311509e70706a13458f87ea99
	https://git.kernel.org/stable/c/211f514ebf1ef5de37b1cf6df9d28a56cfd242ca