CVE-2026-89727: KVM: arm64: GICv2: Don't WARN on out-of-range GICV_DIR INTID

CVE-2026-89727: KVM: arm64: GICv2: Don't WARN on out-of-range GICV_DIR INTID

[Greg Kroah-Hartman]

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

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

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

KVM: arm64: GICv2: Don't WARN on out-of-range GICV_DIR INTID

vgic_v2_deactivate() passes the INTID a guest wrote to GICV_DIR straight
to vgic_get_vcpu_irq(), and treats a failed lookup as a "can't happen"
condition with WARN_ON_ONCE().

The guest can make it happen at will, though: for any INTID outside of
the implemented SGI, PPI and SPI ranges the lookup returns NULL, since
GICv2 has no LPIs. A guest running with EOImode==1 writing such an INTID
to GICV_DIR triggers the WARN, and panics hosts running with
panic_on_warn.

Drop the WARN and ignore failed lookups.

The Linux kernel CVE team has assigned CVE-2026-89727 to this issue.


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

	Issue introduced in 6.19 with commit 255de897e7fb918a34845167c572b5bf8e1d9d79 and fixed in 7.2.4 with commit 78b95c571d021391153a5ac7981e9e4d5cc856a3
	Issue introduced in 6.19 with commit 255de897e7fb918a34845167c572b5bf8e1d9d79 and fixed in 7.3-rc1 with commit c6d9c8ac6521d3049ec90ac58bebd23ed03ac496

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-2026-89727
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-v2.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/78b95c571d021391153a5ac7981e9e4d5cc856a3
	https://git.kernel.org/stable/c/c6d9c8ac6521d3049ec90ac58bebd23ed03ac496