From 501514d6ebd2111c353a1296f25dbe22fbd64657 Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Fri, 4 Sep 2026 21:45:13 +0800 Subject: [PATCH] LoongArch: KVM: Validate MSI data before routing it to EIOINTC pch_msi_set_irq() passes e->msi.data straight into eiointc_set_irq() as the irq number. The MSI data comes from userspace, that either via a KVM_IRQ_ROUTING_MSI entry set with KVM_SET_GSI_ROUTING (used by irqfd and KVM_IRQ_LINE) or directly via KVM_SIGNAL_MSI, and is never checked against EIOINTC_IRQS. eiointc_set_irq() uses the value with __set_bit()/__clear_bit() on the 256-bit isr bitmap, eiointc_update_irq() then indexes sw_coremap[] and the per-cpu coreisr/sw_coreisr bitmaps with it. Therefore a data value >= 256 reads and writes memory past the end of those arrays, i.e. any process holding a VM fd can corrupt kernel memory beyond the allocation of loongarch_eiointc. Reject MSI data that doesn't fit in the EIOINTC irq space. The DMSINTC path is unaffected as it decodes the vector from the address and masks it. Cc: stable@vger.kernel.org Fixes: 1928254c5ccb ("LoongArch: KVM: Add irqfd support") Reported-by: Sashiko Closes: https://lore.kernel.org/all/20260531140921.1B1181F00893@smtp.kernel.org/ Reviewed-by: Tao Cui Reviewed-by: Bibo Mao Signed-off-by: Zeng Chi Signed-off-by: Huacai Chen --- arch/loongarch/kvm/intc/pch_pic.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/loongarch/kvm/intc/pch_pic.c b/arch/loongarch/kvm/intc/pch_pic.c index 83fa2386cf81..2b63b0c2c7ce 100644 --- a/arch/loongarch/kvm/intc/pch_pic.c +++ b/arch/loongarch/kvm/intc/pch_pic.c @@ -78,6 +78,9 @@ int pch_msi_set_irq(struct kvm *kvm, struct kvm_kernel_irq_routing_entry *e, int return dmsintc_set_irq(kvm, msg_addr, e->msi.data, level); } + if (e->msi.data >= EIOINTC_IRQS) + return -EINVAL; + eiointc_set_irq(kvm->arch.eiointc, e->msi.data, level); return 0;