CVE-2026-64290: iommufd: Break the loop on failure in iommufd_fault_fops_read()

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

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

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

iommufd: Break the loop on failure in iommufd_fault_fops_read()

On a copy_to_user() failure inside the inner list_for_each_entry, only the
inner loop breaks; the outer while re-fetches the just-restored fault group
and retries the failing copy_to_user() forever, spinning the reader at 100%
CPU with fault->mutex held.

Check rc after the inner loop and break the outer while as well.

The Linux kernel CVE team has assigned CVE-2026-64290 to this issue.


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

	Issue introduced in 6.11 with commit 07838f7fd529c8a6de44b601d4b7057e6c8d36ed and fixed in 6.18.39 with commit 5539da127d03c1f6c2e2a49fdfbe331a0ccbdea8
	Issue introduced in 6.11 with commit 07838f7fd529c8a6de44b601d4b7057e6c8d36ed and fixed in 7.1.4 with commit f66c16b175509642ee7082df57c9bf3deaebae1a
	Issue introduced in 6.11 with commit 07838f7fd529c8a6de44b601d4b7057e6c8d36ed and fixed in 7.2-rc1 with commit 172fc8b19825a0f5884c38f2289188284e2d45ee

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-2026-64290
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/iommufd/eventq.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/5539da127d03c1f6c2e2a49fdfbe331a0ccbdea8
	https://git.kernel.org/stable/c/f66c16b175509642ee7082df57c9bf3deaebae1a
	https://git.kernel.org/stable/c/172fc8b19825a0f5884c38f2289188284e2d45ee