Subject: CVE-2022-48894: iommu/arm-smmu-v3: Don't unregister on shutdown

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

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

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

iommu/arm-smmu-v3: Don't unregister on shutdown

Similar to SMMUv2, this driver calls iommu_device_unregister() from the
shutdown path, which removes the IOMMU groups with no coordination
whatsoever with their users - shutdown methods are optional in device
drivers. This can lead to NULL pointer dereferences in those drivers'
DMA API calls, or worse.

Instead of calling the full arm_smmu_device_remove() from
arm_smmu_device_shutdown(), let's pick only the relevant function call -
arm_smmu_device_disable() - more or less the reverse of
arm_smmu_device_reset() - and call just that from the shutdown path.

The Linux kernel CVE team has assigned CVE-2022-48894 to this issue.

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

	Issue introduced in 6.1 with commit 57365a04c921 and fixed in 6.1.7 with commit ead3e6c79479
	Issue introduced in 6.1 with commit 57365a04c921 and fixed in 6.2 with commit 32ea2c57dc21

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-2022-48894
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/iommu/arm/arm-smmu-v3/arm-smmu-v3.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/ead3e6c79479890444c777fd329afc125fecde48
	https://git.kernel.org/stable/c/32ea2c57dc216b6ad8125fa680d31daa5d421c95