From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758977Ab3EGEab (ORCPT ); Tue, 7 May 2013 00:30:31 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:25931 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932607Ab3EGEZ5 (ORCPT ); Tue, 7 May 2013 00:25:57 -0400 X-Authority-Analysis: v=2.0 cv=cOZiQyiN c=1 sm=0 a=rXTBtCOcEpjy1lPqhTCpEQ==:17 a=mNMOxpOpBa8A:10 a=Ciwy3NGCPMMA:10 a=BeX6n8KoOMYA:10 a=5SG0PmZfjMsA:10 a=bbbx4UPp9XUA:10 a=meVymXHHAAAA:8 a=TymciAGTofkA:10 a=1XWaLZrsAAAA:8 a=20KFwNOVAAAA:8 a=fC4T7qsy4_4xvlMS5R0A:9 a=UTB_XpHje0EA:10 a=jEp0ucaQiEUA:10 a=jeBq3FmKZ4MA:10 a=-cyeKQDD62-ZVCI4:21 a=oJRY0AgXXGG1ERsd:21 a=rXTBtCOcEpjy1lPqhTCpEQ==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 74.67.115.198 Message-Id: <20130507035852.058901437@goodmis.org> User-Agent: quilt/0.60-1 Date: Mon, 06 May 2013 23:58:19 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Andrew Honig , Marcelo Tosatti Subject: [067/126] KVM: x86: fix for buffer overflow in handling of MSR_KVM_SYSTEM_TIME (CVE-2013-1796) References: <20130507035712.909872333@goodmis.org> Content-Disposition: inline; filename=0067-KVM-x86-fix-for-buffer-overflow-in-handling-of-MSR_K.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.6.11.3 stable review patch. If anyone has any objections, please let me know. ------------------ From: Andy Honig [ Upstream commit c300aa64ddf57d9c5d9c898a64b36877345dd4a9 ] If the guest sets the GPA of the time_page so that the request to update the time straddles a page then KVM will write onto an incorrect page. The write is done byusing kmap atomic to get a pointer to the page for the time structure and then performing a memcpy to that page starting at an offset that the guest controls. Well behaved guests always provide a 32-byte aligned address, however a malicious guest could use this to corrupt host kernel memory. Tested: Tested against kvmclock unit test. Signed-off-by: Andrew Honig Signed-off-by: Marcelo Tosatti Signed-off-by: Steven Rostedt --- arch/x86/kvm/x86.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a201790..142e18a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1636,6 +1636,11 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data) /* ...but clean it before doing the actual write */ vcpu->arch.time_offset = data & ~(PAGE_MASK | 1); + /* Check that the address is 32-byte aligned. */ + if (vcpu->arch.time_offset & + (sizeof(struct pvclock_vcpu_time_info) - 1)) + break; + vcpu->arch.time_page = gfn_to_page(vcpu->kvm, data >> PAGE_SHIFT); -- 1.7.10.4