From 1d6a821277aaa0cdd666278aaff93298df313d41 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Mon, 15 Feb 2016 17:04:04 +0000 Subject: [PATCH] arm/arm64: KVM: Feed initialized memory to MMIO accesses On an MMIO access, we always copy the on-stack buffer info the shared "run" structure, even if this is a read access. This ends up leaking up to 8 bytes of uninitialized memory into userspace, depending on the size of the access. An obvious fix for this one is to only perform the copy if this is an actual write. Reviewed-by: Christoffer Dall Signed-off-by: Marc Zyngier --- arch/arm/kvm/mmio.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c index 7f33b2056ae6..0f6600f05137 100644 --- a/arch/arm/kvm/mmio.c +++ b/arch/arm/kvm/mmio.c @@ -206,7 +206,8 @@ int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run, run->mmio.is_write = is_write; run->mmio.phys_addr = fault_ipa; run->mmio.len = len; - memcpy(run->mmio.data, data_buf, len); + if (is_write) + memcpy(run->mmio.data, data_buf, len); if (!ret) { /* We handled the access successfully in the kernel. */ -- 2.20.1