From d38ea9579ce34dfe22378788e99f26eab31ea064 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 26 May 2022 21:08:17 +0000 Subject: [PATCH] KVM: x86: Bug the VM on an out-of-bounds data read Bug the VM and terminate emulation if an out-of-bounds read into the emulator's data cache occurs. Knowingly contuining on all but guarantees that KVM will overwrite random kernel data, which is far, far worse than killing the VM. Signed-off-by: Sean Christopherson Reviewed-by: Kees Cook Reviewed-by: Vitaly Kuznetsov Message-Id: <20220526210817.3428868-9-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/emulate.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 2aa17462a9ac..39ea9138224c 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1373,7 +1373,8 @@ static int read_emulated(struct x86_emulate_ctxt *ctxt, if (mc->pos < mc->end) goto read_cached; - WARN_ON((mc->end + size) >= sizeof(mc->data)); + if (KVM_EMULATOR_BUG_ON((mc->end + size) >= sizeof(mc->data), ctxt)) + return X86EMUL_UNHANDLEABLE; rc = ctxt->ops->read_emulated(ctxt, addr, mc->data + mc->end, size, &ctxt->exception);