From patchwork Mon Feb 25 11:49:47 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tyler Hicks X-Patchwork-Id: 1047697 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=lists.ubuntu.com (client-ip=91.189.94.19; helo=huckleberry.canonical.com; envelope-from=kernel-team-bounces@lists.ubuntu.com; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=canonical.com Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 447Kxx3JLvz9s71; Mon, 25 Feb 2019 22:50:13 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.86_2) (envelope-from ) id 1gyEls-0002Je-Oa; Mon, 25 Feb 2019 11:50:08 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.86_2) (envelope-from ) id 1gyElr-0002JL-4l for kernel-team@lists.ubuntu.com; Mon, 25 Feb 2019 11:50:07 +0000 Received: from mb52736d0.tmodns.net ([208.54.39.181] helo=sec.lxd) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1gyElp-0001cM-Vo; Mon, 25 Feb 2019 11:50:06 +0000 From: Tyler Hicks To: kernel-team@lists.ubuntu.com Subject: [PATCH 1/2] kvm: fix kvm_ioctl_create_device() reference counting (CVE-2019-6974) Date: Mon, 25 Feb 2019 11:49:47 +0000 Message-Id: <1551095388-1158-2-git-send-email-tyhicks@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1551095388-1158-1-git-send-email-tyhicks@canonical.com> References: <1551095388-1158-1-git-send-email-tyhicks@canonical.com> X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Jann Horn kvm_ioctl_create_device() does the following: 1. creates a device that holds a reference to the VM object (with a borrowed reference, the VM's refcount has not been bumped yet) 2. initializes the device 3. transfers the reference to the device to the caller's file descriptor table 4. calls kvm_get_kvm() to turn the borrowed reference to the VM into a real reference The ownership transfer in step 3 must not happen before the reference to the VM becomes a proper, non-borrowed reference, which only happens in step 4. After step 3, an attacker can close the file descriptor and drop the borrowed reference, which can cause the refcount of the kvm object to drop to zero. This means that we need to grab a reference for the device before anon_inode_getfd(), otherwise the VM can disappear from under us. Fixes: 852b6d57dc7f ("kvm: add device control API") Cc: stable@kernel.org Signed-off-by: Jann Horn Signed-off-by: Paolo Bonzini CVE-2019-6974 (backported from commit cfa39381173d5f969daf43582c95ad679189cbc9) [tyhicks: Backport to 4.4: - Contextual changes due to missing upstream commit a28ebea2adc4] Signed-off-by: Tyler Hicks --- virt/kvm/kvm_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 9d2277f69ce6..5f35e6c1c2d1 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2328,14 +2328,15 @@ static int kvm_ioctl_create_device(struct kvm *kvm, return ret; } + kvm_get_kvm(kvm); ret = anon_inode_getfd(ops->name, &kvm_device_fops, dev, O_RDWR | O_CLOEXEC); if (ret < 0) { + kvm_put_kvm(kvm); ops->destroy(dev); return ret; } list_add(&dev->vm_node, &kvm->devices); - kvm_get_kvm(kvm); cd->fd = ret; return 0; } From patchwork Mon Feb 25 11:49:48 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tyler Hicks X-Patchwork-Id: 1047698 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=lists.ubuntu.com (client-ip=91.189.94.19; helo=huckleberry.canonical.com; envelope-from=kernel-team-bounces@lists.ubuntu.com; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=canonical.com Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 447Ky04ZdBz9s6w; Mon, 25 Feb 2019 22:50:16 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.86_2) (envelope-from ) id 1gyElv-0002L2-Sy; Mon, 25 Feb 2019 11:50:11 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.86_2) (envelope-from ) id 1gyElu-0002KT-Jb for kernel-team@lists.ubuntu.com; Mon, 25 Feb 2019 11:50:10 +0000 Received: from mb52736d0.tmodns.net ([208.54.39.181] helo=sec.lxd) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1gyElt-0001cM-7H; Mon, 25 Feb 2019 11:50:10 +0000 From: Tyler Hicks To: kernel-team@lists.ubuntu.com Subject: [PATCH 2/2] KVM: x86: work around leak of uninitialized stack contents (CVE-2019-7222) Date: Mon, 25 Feb 2019 11:49:48 +0000 Message-Id: <1551095388-1158-3-git-send-email-tyhicks@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1551095388-1158-1-git-send-email-tyhicks@canonical.com> References: <1551095388-1158-1-git-send-email-tyhicks@canonical.com> X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Paolo Bonzini Bugzilla: 1671930 Emulation of certain instructions (VMXON, VMCLEAR, VMPTRLD, VMWRITE with memory operand, INVEPT, INVVPID) can incorrectly inject a page fault when passed an operand that points to an MMIO address. The page fault will use uninitialized kernel stack memory as the CR2 and error code. The right behavior would be to abort the VM with a KVM_EXIT_INTERNAL_ERROR exit to userspace; however, it is not an easy fix, so for now just ensure that the error code and CR2 are zero. Embargoed until Feb 7th 2019. Reported-by: Felix Wilhelm Cc: stable@kernel.org Signed-off-by: Paolo Bonzini CVE-2019-7222 (cherry picked from commit 353c0956a618a07ba4bbe7ad00ff29fe70e8412a) Signed-off-by: Tyler Hicks --- arch/x86/kvm/x86.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 205c7f5a96f9..f5c39b5a9a8f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4084,6 +4084,13 @@ int kvm_read_guest_virt(struct x86_emulate_ctxt *ctxt, struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt); u32 access = (kvm_x86_ops->get_cpl(vcpu) == 3) ? PFERR_USER_MASK : 0; + /* + * FIXME: this should call handle_emulation_failure if X86EMUL_IO_NEEDED + * is returned, but our callers are not ready for that and they blindly + * call kvm_inject_page_fault. Ensure that they at least do not leak + * uninitialized kernel stack memory into cr2 and error code. + */ + memset(exception, 0, sizeof(*exception)); return kvm_read_guest_virt_helper(addr, val, bytes, vcpu, access, exception); }