diff options
Diffstat (limited to 'KVM-x86-Reload-pit-counters-for-all-channels-when-re.patch')
| -rw-r--r-- | KVM-x86-Reload-pit-counters-for-all-channels-when-re.patch | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/KVM-x86-Reload-pit-counters-for-all-channels-when-re.patch b/KVM-x86-Reload-pit-counters-for-all-channels-when-re.patch new file mode 100644 index 000000000..a9d88a009 --- /dev/null +++ b/KVM-x86-Reload-pit-counters-for-all-channels-when-re.patch @@ -0,0 +1,59 @@ +From f3b9db45027a40369fe13c4661c4249d1df8c8d0 Mon Sep 17 00:00:00 2001 +From: Andrew Honig <ahonig@google.com> +Date: Wed, 18 Nov 2015 14:50:23 -0800 +Subject: [PATCH] KVM: x86: Reload pit counters for all channels when restoring + state + +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 <ahonig@google.com> +Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> +[Backported to 4.3.y by Josh Boyer <jwboyer@fedoraproject.org>] +--- + arch/x86/kvm/x86.c | 9 ++++++--- + 1 file changed, 6 insertions(+), 3 deletions(-) + +diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c +index 43609af03283..e124f9c8391e 100644 +--- a/arch/x86/kvm/x86.c ++++ b/arch/x86/kvm/x86.c +@@ -3437,10 +3437,11 @@ 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 r = 0; +- ++ 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 r; + } +@@ -3461,6 +3462,7 @@ 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 r = 0, 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; +@@ -3470,7 +3472,8 @@ 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 r; + } +-- +2.5.0 + |