From patchwork Tue Oct 23 21:32:22 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jim Mattson X-Patchwork-Id: 10653689 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8F83613A4 for ; Tue, 23 Oct 2018 21:32:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7B4DF2A38F for ; Tue, 23 Oct 2018 21:32:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6FD5F2A39B; Tue, 23 Oct 2018 21:32:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, USER_IN_DEF_DKIM_WL autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BACFA2A38F for ; Tue, 23 Oct 2018 21:32:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726992AbeJXF5m (ORCPT ); Wed, 24 Oct 2018 01:57:42 -0400 Received: from mail-qt1-f201.google.com ([209.85.160.201]:46648 "EHLO mail-qt1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725985AbeJXF5m (ORCPT ); Wed, 24 Oct 2018 01:57:42 -0400 Received: by mail-qt1-f201.google.com with SMTP id j63-v6so3378993qte.13 for ; Tue, 23 Oct 2018 14:32:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=4wvJWnkk/E5vWP7sAfEx9G5mBihgqckEwzTwPTz/UMQ=; b=s91c3mFmHKuS7bYGnFl+QgwW/y2aWjQB5+c5hzgDlXXbqFUbsSPHuNVjVnecVbCEIc jD78VGrwSBRkoWBEqLIzguFtgnzrTEMqSVPpwi1Vm+rU+4Qigv6fCg3z+O5NgJxhYQ/o RsUsEjebOQYACIQfk86p+lSakZJnJcmx9bSrqzydh4tGfsdImzyXDcFApp6nTr4B5KfU hzj2MIUKAiD8cve7nJmzeCf3yMKkhWPZy+/LOOMq7ZyYP9iN+2iJDuCB88Yl5U3646DK TVpH4gwngzL6EV2jXLh3UI8OLGyQ1p/bDPEAgSJshsf2ngP10dQl453SqbIM24mXpJDV 7JLg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=4wvJWnkk/E5vWP7sAfEx9G5mBihgqckEwzTwPTz/UMQ=; b=KAV/k1XTPPDeKDoFakcrixj6AP7tvhjcbhuYiciTzqXFq1/ufDpeIuQ2T8mDDfhELz uzpYRSsI6qeGXgwTLHoIvjawrzwV8El6wk+C4sjcdBsXxdRfRpMTa3iTjqmZMGIQhcLJ tJAvQcwk3Xe+5M3HbVjLD8EXzA2FfrScKs58EA/yMqYXwKjQgGSkEVDoyRRge64Xl8pX pztD2slp2jxSSUDLCV23j/oR6SQXOW93ybVmKuRZ2z/3JKwQoJ0gfGy8JpvwWAZ0JpvR Y1KkvcGhmetqSx7Gk1cSOqDGBXQ2YmwRrrP3Y/P6wvgX22/aERfPb5e8AWpXDthgRzsM gmSA== X-Gm-Message-State: AGRZ1gK2ctlzhWTp8LhRgKMK7cwiHG/h5HyCv+QFfDagsos92QGTv5GD wXKs1kjjmVYSLHHHqAeA2/ubtRMP6Wqxsa2w9x+T+euFocSIEvjMcVxnxiOcpdSGKkBCLVYQC6E YWv8JwffH8PQ9GoOvQQd2rUqhR2tuZNtKWgy9dci2+Wr6z6EuK+uLporiAjbq4qg= X-Google-Smtp-Source: AJdET5ekTH0Vd03rnpnG24ChUCw7zB+8Sx7BdJKJkJSE5MXAA28wXYpv1OzPrHyggyasriL0KCGot6oIIIghig== X-Received: by 2002:ae9:c209:: with SMTP id j9-v6mr2998166qkg.1.1540330350974; Tue, 23 Oct 2018 14:32:30 -0700 (PDT) Date: Tue, 23 Oct 2018 14:32:22 -0700 In-Reply-To: <20181015165742.38393-2-jmattson@google.com> Message-Id: <20181023213222.259677-1-jmattson@google.com> Mime-Version: 1.0 References: <20181015165742.38393-2-jmattson@google.com> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog Subject: [PATCH v4] kvm: x86: Disallow invalid exceptions from userspace From: Jim Mattson To: kvm@vger.kernel.org Cc: Jim Mattson Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Userspace should not be able to inject an invalid exception into a kvm guest via KVM_SET_VCPU_EVENTS, nor should it be able to convert a valid pending exception to an invalid one via KVM_SET_SREGS. In particular, only certain exceptions deliver an error code in protected mode, and no exception delivers an error code in real-address mode. Reported-by: syzbot Signed-off-by: Jim Mattson Reviewed-by: Krish Sadhukhan --- arch/x86/kvm/x86.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 66d66d77caee..47b4d1099467 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3528,9 +3528,18 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu, events->exception_has_payload = 0; } - if ((events->exception.injected || events->exception.pending) && - (events->exception.nr > 31 || events->exception.nr == NMI_VECTOR)) - return -EINVAL; + if (events->exception.injected || events->exception.pending) { + bool needs_error_code; + + if (events->exception.nr > 31 || + events->exception.nr == NMI_VECTOR) + return -EINVAL; + + needs_error_code = is_protmode(vcpu) && + x86_exception_has_error_code(events->exception.nr); + if (!!events->exception.has_error_code != needs_error_code) + return -EINVAL; + } /* INITs are latched while in SMM */ if (events->flags & KVM_VCPUEVENT_VALID_SMM && @@ -8312,6 +8321,18 @@ static int kvm_valid_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) return -EINVAL; } + /* + * Switching between real-address mode and protected mode can + * potentially invalidate a pending exception. + */ + if (vcpu->arch.exception.injected || vcpu->arch.exception.pending) { + bool needs_error_code = (sregs->cr0 & X86_CR0_PE) && + x86_exception_has_error_code(vcpu->arch.exception.nr); + + if (vcpu->arch.exception.has_error_code != needs_error_code) + return -EINVAL; + } + return 0; }