Subject: CVE-2021-46967: vhost-vdpa: fix vm_flags for virtqueue doorbell mapping

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

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

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

vhost-vdpa: fix vm_flags for virtqueue doorbell mapping

The virtqueue doorbell is usually implemented via registeres but we
don't provide the necessary vma->flags like VM_PFNMAP. This may cause
several issues e.g when userspace tries to map the doorbell via vhost
IOTLB, kernel may panic due to the page is not backed by page
structure. This patch fixes this by setting the necessary
vm_flags. With this patch, try to map doorbell via IOTLB will fail
with bad address.

The Linux kernel CVE team has assigned CVE-2021-46967 to this issue.

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

	Issue introduced in 5.8 with commit ddd89d0a059d and fixed in 5.10.36 with commit 3b8b6399666a
	Issue introduced in 5.8 with commit ddd89d0a059d and fixed in 5.11.20 with commit 940230a5c31e
	Issue introduced in 5.8 with commit ddd89d0a059d and fixed in 5.12.3 with commit 93dbbf20e3ff
	Issue introduced in 5.8 with commit ddd89d0a059d and fixed in 5.13 with commit 3a3e0fad16d4

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-2021-46967
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/vhost/vdpa.c

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/3b8b6399666a29daa30b0bb3f5c9e3fc81c5a6a6
	https://git.kernel.org/stable/c/940230a5c31e2714722aee04c521a21f484b4df7
	https://git.kernel.org/stable/c/93dbbf20e3ffad14f04227a0b7105f6e6f0387ce
	https://git.kernel.org/stable/c/3a3e0fad16d40a2aa68ddf7eea4acdf48b22dd44