Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754005AbcDVLHi (ORCPT ); Fri, 22 Apr 2016 07:07:38 -0400 Received: from mx2.suse.de ([195.135.220.15]:44217 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753884AbcDVLGl (ORCPT ); Fri, 22 Apr 2016 07:06:41 -0400 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Andrew Honig , Paolo Bonzini , Jiri Slaby Subject: [PATCH 3.12 78/78] KVM: x86: Reload pit counters for all channels when restoring state Date: Fri, 22 Apr 2016 13:06:01 +0200 Message-Id: X-Mailer: git-send-email 2.8.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2248 Lines: 59 From: Andrew Honig 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 0185604c2d82c560dab2f2933a18f797e74ab5a8 upstream. Currently if userspace restores the pit counters with a count of 0 on channels 1 or 2 and the guest attempts to read the count on those channels, then KVM will perform a mod of 0 and crash. This will ensure that 0 values are converted to 65536 as per the spec. This is CVE-2015-7513. Signed-off-by: Andy Honig Signed-off-by: Paolo Bonzini Signed-off-by: Jiri Slaby --- arch/x86/kvm/x86.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 1962a3999adf..e0c859e1999a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3479,9 +3479,11 @@ static int kvm_vm_ioctl_get_pit(struct kvm *kvm, struct kvm_pit_state *ps) static int kvm_vm_ioctl_set_pit(struct kvm *kvm, struct kvm_pit_state *ps) { + int i; mutex_lock(&kvm->arch.vpit->pit_state.lock); memcpy(&kvm->arch.vpit->pit_state, ps, sizeof(struct kvm_pit_state)); - kvm_pit_load_count(kvm, 0, ps->channels[0].count, 0); + for (i = 0; i < 3; i++) + kvm_pit_load_count(kvm, i, ps->channels[i].count, 0); mutex_unlock(&kvm->arch.vpit->pit_state.lock); return 0; } @@ -3500,6 +3502,7 @@ static int kvm_vm_ioctl_get_pit2(struct kvm *kvm, struct kvm_pit_state2 *ps) static int kvm_vm_ioctl_set_pit2(struct kvm *kvm, struct kvm_pit_state2 *ps) { int start = 0; + int i; u32 prev_legacy, cur_legacy; mutex_lock(&kvm->arch.vpit->pit_state.lock); prev_legacy = kvm->arch.vpit->pit_state.flags & KVM_PIT_FLAGS_HPET_LEGACY; @@ -3509,7 +3512,8 @@ static int kvm_vm_ioctl_set_pit2(struct kvm *kvm, struct kvm_pit_state2 *ps) memcpy(&kvm->arch.vpit->pit_state.channels, &ps->channels, sizeof(kvm->arch.vpit->pit_state.channels)); kvm->arch.vpit->pit_state.flags = ps->flags; - kvm_pit_load_count(kvm, 0, kvm->arch.vpit->pit_state.channels[0].count, start); + for (i = 0; i < 3; i++) + kvm_pit_load_count(kvm, i, kvm->arch.vpit->pit_state.channels[i].count, start); mutex_unlock(&kvm->arch.vpit->pit_state.lock); return 0; } -- 2.8.1