Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967191Ab3DRJ3o (ORCPT ); Thu, 18 Apr 2013 05:29:44 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:40160 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757479Ab3DRJR4 (ORCPT ); Thu, 18 Apr 2013 05:17:56 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Andrew Honig , Marcelo Tosatti , Luis Henriques Subject: [PATCH 35/72] KVM: x86: Convert MSR_KVM_SYSTEM_TIME to use gfn_to_hva_cache functions (CVE-2013-1797) Date: Thu, 18 Apr 2013 10:16:20 +0100 Message-Id: <1366276617-3553-36-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1366276617-3553-1-git-send-email-luis.henriques@canonical.com> References: <1366276617-3553-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5052 Lines: 157 3.5.7.11 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Andy Honig commit 0b79459b482e85cb7426aa7da683a9f2c97aeae1 upstream. There is a potential use after free issue with the handling of MSR_KVM_SYSTEM_TIME. If the guest specifies a GPA in a movable or removable memory such as frame buffers then KVM might continue to write to that address even after it's removed via KVM_SET_USER_MEMORY_REGION. KVM pins the page in memory so it's unlikely to cause an issue, but if the user space component re-purposes the memory previously used for the guest, then the guest will be able to corrupt that memory. Tested: Tested against kvmclock unit test Signed-off-by: Andrew Honig Signed-off-by: Marcelo Tosatti [ luis: backported to 3.5: - Adjust context - Removed references to PVCLOCK_GUEST_STOPPED ] Signed-off-by: Luis Henriques --- arch/x86/include/asm/kvm_host.h | 4 ++-- arch/x86/kvm/x86.c | 40 +++++++++++++++------------------------- 2 files changed, 17 insertions(+), 27 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index db7c1f2..9a50912 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -410,8 +410,8 @@ struct kvm_vcpu_arch { gpa_t time; struct pvclock_vcpu_time_info hv_clock; unsigned int hw_tsc_khz; - unsigned int time_offset; - struct page *time_page; + struct gfn_to_hva_cache pv_time; + bool pv_time_enabled; struct { u64 msr_val; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ad5cf4b..5b4ac78 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1118,7 +1118,6 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) { unsigned long flags; struct kvm_vcpu_arch *vcpu = &v->arch; - void *shared_kaddr; unsigned long this_tsc_khz; s64 kernel_ns, max_kernel_ns; u64 tsc_timestamp; @@ -1154,7 +1153,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) local_irq_restore(flags); - if (!vcpu->time_page) + if (!vcpu->pv_time_enabled) return 0; /* @@ -1212,14 +1211,9 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) */ vcpu->hv_clock.version += 2; - shared_kaddr = kmap_atomic(vcpu->time_page); - - memcpy(shared_kaddr + vcpu->time_offset, &vcpu->hv_clock, - sizeof(vcpu->hv_clock)); - - kunmap_atomic(shared_kaddr); - - mark_page_dirty(v->kvm, vcpu->time >> PAGE_SHIFT); + kvm_write_guest_cached(v->kvm, &vcpu->pv_time, + &vcpu->hv_clock, + sizeof(vcpu->hv_clock)); return 0; } @@ -1508,10 +1502,7 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data) static void kvmclock_reset(struct kvm_vcpu *vcpu) { - if (vcpu->arch.time_page) { - kvm_release_page_dirty(vcpu->arch.time_page); - vcpu->arch.time_page = NULL; - } + vcpu->arch.pv_time_enabled = false; } static void accumulate_steal_time(struct kvm_vcpu *vcpu) @@ -1606,6 +1597,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data) break; case MSR_KVM_SYSTEM_TIME_NEW: case MSR_KVM_SYSTEM_TIME: { + u64 gpa_offset; kvmclock_reset(vcpu); vcpu->arch.time = data; @@ -1615,21 +1607,18 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data) if (!(data & 1)) break; - /* ...but clean it before doing the actual write */ - vcpu->arch.time_offset = data & ~(PAGE_MASK | 1); + gpa_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)) + if (gpa_offset & (sizeof(struct pvclock_vcpu_time_info) - 1)) break; - vcpu->arch.time_page = - gfn_to_page(vcpu->kvm, data >> PAGE_SHIFT); + if (kvm_gfn_to_hva_cache_init(vcpu->kvm, + &vcpu->arch.pv_time, data & ~1ULL)) + vcpu->arch.pv_time_enabled = false; + else + vcpu->arch.pv_time_enabled = true; - if (is_error_page(vcpu->arch.time_page)) { - kvm_release_page_clean(vcpu->arch.time_page); - vcpu->arch.time_page = NULL; - } break; } case MSR_KVM_ASYNC_PF_EN: @@ -2616,7 +2605,7 @@ static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu *vcpu, static int kvm_set_guest_paused(struct kvm_vcpu *vcpu) { struct pvclock_vcpu_time_info *src = &vcpu->arch.hv_clock; - if (!vcpu->arch.time_page) + if (!vcpu->arch.pv_time_enabled) return -EINVAL; src->flags |= PVCLOCK_GUEST_STOPPED; mark_page_dirty(vcpu->kvm, vcpu->arch.time >> PAGE_SHIFT); @@ -6216,6 +6205,7 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu) if (!zalloc_cpumask_var(&vcpu->arch.wbinvd_dirty_mask, GFP_KERNEL)) goto fail_free_mce_banks; + vcpu->arch.pv_time_enabled = false; kvm_async_pf_hash_reset(vcpu); kvm_pmu_init(vcpu); -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/