CVE-2026-52952: iommu: Fix WARN_ON in __iommu_group_set_domain_nofail() due to reset

CVE-2026-52952: iommu: Fix WARN_ON in __iommu_group_set_domain_nofail() due to reset

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

iommu: Fix WARN_ON in __iommu_group_set_domain_nofail() due to reset

In __iommu_group_set_domain_internal(), concurrent domain attachments are
rejected when any device in the group is recovering. This is necessary to
fence concurrent attachments to a multi-device group where devices might
share the same RID due to PCI DMA alias quirks, but triggers the WARN_ON in
__iommu_group_set_domain_nofail().

Other IOMMU_SET_DOMAIN_MUST_SUCCEED callers in detach/teardown paths, such
as __iommu_group_set_core_domain and __iommu_release_dma_ownership, should
not be rejected, as the domain would be freed anyway in these nofail paths
while group->domain is still pointing to it. So pci_dev_reset_iommu_done()
could trigger a UAF when re-attaching group->domain.

Honor the IOMMU_SET_DOMAIN_MUST_SUCCEED flag, allowing the callers through
the group->recovery_cnt fence, so as to update the group->domain pointer.
Instead add a gdev->blocked check in the device iteration loop, to prevent
any concurrent per-device detachment.

The Linux kernel CVE team has assigned CVE-2026-52952 to this issue.


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

	Issue introduced in 7.0 with commit c279e83953d937470f8a6e69b69f62608714f13f and fixed in 7.0.10 with commit 8fc289e809f3eb7e36cadc4684ab6fad747a5a93
	Issue introduced in 7.0 with commit c279e83953d937470f8a6e69b69f62608714f13f and fixed in 7.1 with commit 5474e6e17a262db45c60575c73f70210f5c7001f

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-2026-52952
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/iommu.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/8fc289e809f3eb7e36cadc4684ab6fad747a5a93
	https://git.kernel.org/stable/c/5474e6e17a262db45c60575c73f70210f5c7001f