From 9b10fb74e4b661543d188701bd4d024fc5c18f58 Mon Sep 17 00:00:00 2001 From: Fuad Tabba Date: Fri, 7 Aug 2026 11:41:01 +0100 Subject: [PATCH] KVM: arm64: vgic-its: Don't save collections the table cannot hold A guest that disables the ITS and rewrites GITS_BASER with fewer pages, VALID still set, keeps every collection it mapped against the larger table: KVM stores the new BASER unconditionally and frees the list only when VALID is cleared. vgic_its_save_collection_table() then walks the whole list, writing up to 448K past the end of the table, and saves collection IDs that vgic_its_restore_cte() rejects, so the save succeeds and the restore fails with -EINVAL on the destination. The overrun stays in guest memory, as vgic_write_guest_lock() validates every gfn. Validate each collection against the current table with vgic_its_check_id() and return -EINVAL, as vgic_its_save_device_tables() does for devices. Collection IDs are unique and the collection table is never indirect, so the check also bounds the walk. Fixes: ea1ad53e1e31a ("KVM: arm64: vgic-its: Collection table save/restore") Signed-off-by: Fuad Tabba Link: https://patch.msgid.link/20260807104102.2410744-4-fuad.tabba@linux.dev Signed-off-by: Oliver Upton --- arch/arm64/kvm/vgic/vgic-its.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c index 6f3ea75b4c23..d8b784f69abc 100644 --- a/arch/arm64/kvm/vgic/vgic-its.c +++ b/arch/arm64/kvm/vgic/vgic-its.c @@ -2529,6 +2529,9 @@ static int vgic_its_save_collection_table(struct vgic_its *its) max_size = GITS_BASER_NR_PAGES(baser) * SZ_64K; list_for_each_entry(collection, &its->collection_list, coll_list) { + if (!vgic_its_check_id(its, baser, collection->collection_id, NULL)) + return -EINVAL; + ret = vgic_its_save_cte(its, collection, gpa); if (ret) return ret;