CVE-2026-72288: KVM: arm64: vgic: Handle race between interrupt affinity change and LPI disabling

CVE-2026-72288: KVM: arm64: vgic: Handle race between interrupt affinity change and LPI disabling

[Greg Kroah-Hartman]

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

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

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

KVM: arm64: vgic: Handle race between interrupt affinity change and LPI disabling

Hyunwoo Kim reports some really bad races should the following
situation occur:

- LPI-I is pending in vcpu-B's AP list
- vcpu-A writes to vcpu-B's RD to disable its LPIs
- vcpu-C moves I from B to C

If the last two race nicely enough, vgic_prune_ap_list() can drop
the irq and AP list locks, reacquire them, and in the interval
the irq has been freed. UAF follows.

The fix is two-fold:

- Before dropping the irq and ap_list locks, take a reference on
  the irq

- Do not try to handle migration of the pending bit: there is no
  expectation that this state is retained, as per the architecture

With that, we're sure that the interrupt is still around, and we
safely remove it from the AP list as it has no target at this
stage (unless another interrupt fires, but that's another story).

The Linux kernel CVE team has assigned CVE-2026-72288 to this issue.


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

	Issue introduced in 4.8 with commit 5dd4b924e390af426e424d5e52c1b4d1566af817 and fixed in 6.18.40 with commit d19dca8194ebed371e624331c6be2cb73b562caf
	Issue introduced in 4.8 with commit 5dd4b924e390af426e424d5e52c1b4d1566af817 and fixed in 7.1.5 with commit b1a89d12d35a8256d2b170ced0b1c86851f3def2
	Issue introduced in 4.8 with commit 5dd4b924e390af426e424d5e52c1b4d1566af817 and fixed in 7.2-rc4 with commit 7258770e5814f15e8308ebda82ac9acf6964ba8e

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-2026-72288
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:
	arch/arm64/kvm/vgic/vgic.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/d19dca8194ebed371e624331c6be2cb73b562caf
	https://git.kernel.org/stable/c/b1a89d12d35a8256d2b170ced0b1c86851f3def2
	https://git.kernel.org/stable/c/7258770e5814f15e8308ebda82ac9acf6964ba8e