CVE-2026-89912KVM: arm64: vgic-its: Don't dereference a NULL collection on ITT save

Official description

In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: vgic-its: Don't dereference a NULL collection on ITT save MAPC with V=0 drops ite->collection but leaves the ITE on the device's ITT list, and vgic_its_save_ite() dereferences it unconditionally. A guest that issues MAPD, MAPTI and then MAPC(V=0) therefore oopses the host when the VMM issues KVM_DEV_ARM_ITS_SAVE_TABLES to migrate it. That sequence is UNPREDICTABLE per the architecture, but KVM already handles the resulting state in the translate, MOVI and DISCARD paths. Save a zeroed entry, which vgic_its_restore_ite() reads back as invalid. Skipping the ITE instead would leave the ITT slot holding whatever is in guest memory, and restore rejects an entry naming a collection the restored collection table does not have.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/df829e4fe235b3a0dbf830986d81c040d3d2e940
• https://git.kernel.org/stable/c/0fb71211146e39cf67811ccb873d2770a9c129ac
• https://git.kernel.org/stable/c/566d0f99aec92280ce403f22068eb07241a79e2a
• https://git.kernel.org/stable/c/dd0c3e6c03e3bb3fd7c0fa422230020674c5c25e
• https://git.kernel.org/stable/c/2c3a87ad3d3935c43d465cd2465db9020f9e898f
• https://git.kernel.org/stable/c/3d4c26b16a04a084fe0bde08ccdd8086570f8bbe
• https://git.kernel.org/stable/c/36df368861d2664291298feeb37dfef43fcae670
• https://git.kernel.org/stable/c/c6c156d931c33b92362383cf76f6d6e1291dcbfe