From: Michael Bommarito Date: Tue, 19 May 2026 13:25:19 +0000 (-0400) Subject: KVM: arm64: vgic-its: Reject restored DTE with out-of-range num_eventid_bits X-Git-Tag: v7.1-rc5~1^2~6^2~2 X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=9ce754ed8e7ab4e3999767ce1505f85c449ccb07;p=thirdparty%2Fkernel%2Flinux.git KVM: arm64: vgic-its: Reject restored DTE with out-of-range num_eventid_bits Userspace can restore an ITS Device Table Entry whose Size field encodes more EventID bits than the virtual ITS supports. The live MAPD path rejects that state, but vgic_its_restore_dte() accepts it and stores the out-of-range value in dev->num_eventid_bits. Reject restored DTEs with num_eventid_bits > VITS_TYPER_IDBITS before allocating the device. This mirrors the MAPD check and prevents the restored state from reaching vgic_its_restore_itt(), where the unchecked value can be converted into an oversized scan_its_table() range. Fixes: 57a9a117154c ("KVM: arm64: vgic-its: Device table save/restore") Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Michael Bommarito Link: https://lore.kernel.org/r/20260519132519.2142458-1-michael.bommarito@gmail.com Signed-off-by: Marc Zyngier Cc: stable@vger.kernel.org --- diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c index 2ea9f1c7ebcd0..1d7e5d560af4c 100644 --- a/arch/arm64/kvm/vgic/vgic-its.c +++ b/arch/arm64/kvm/vgic/vgic-its.c @@ -2307,6 +2307,10 @@ static int vgic_its_restore_dte(struct vgic_its *its, u32 id, /* dte entry is valid */ offset = (entry & KVM_ITS_DTE_NEXT_MASK) >> KVM_ITS_DTE_NEXT_SHIFT; + /* Mimic the MAPD behaviour and reject invalid EID bits. */ + if (num_eventid_bits > VITS_TYPER_IDBITS) + return -EINVAL; + if (!vgic_its_check_id(its, baser, id, NULL)) return -EINVAL;