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[x86] kvm: Reload pit counters for all channels when restoring state (CVE-2015-7513)

This commit is contained in:
Salvatore Bonaccorso 2015-12-31 15:48:05 +01:00
parent e57c91d886
commit abab5c2745
3 changed files with 56 additions and 0 deletions
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2
debian/changelog vendored
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@ -13,6 +13,8 @@ linux (4.3.3-3) UNRELEASED; urgency=medium
[ Salvatore Bonaccorso ]
* ovl: fix permission checking for setattr (CVE-2015-8660)
* [x86] kvm: Reload pit counters for all channels when restoring state
(CVE-2015-7513)
-- Ben Hutchings <ben@decadent.org.uk> Fri, 18 Dec 2015 20:19:24 +0000

53
debian/patches/bugfix/x86/KVM-x86-Reload-pit-counters-for-all-channels-when-re.patch vendored Normal file
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@ -0,0 +1,53 @@
From: Andrew Honig <ahonig@google.com>
Date: Wed, 18 Nov 2015 14:50:23 -0800
Subject: KVM: x86: Reload pit counters for all channels when restoring state
Origin: https://git.kernel.org/linus/0185604c2d82c560dab2f2933a18f797e74ab5a8
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>
[carnil: Backport to 4.3.3: context]
---
arch/x86/kvm/x86.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3437,10 +3437,11 @@ static int kvm_vm_ioctl_get_pit(struct k
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
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
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;
}

1
debian/patches/series vendored
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@ -127,3 +127,4 @@ bugfix/all/xen-pciback-for-xen_pci_op_disable_msi-x-only-disabl.patch
bugfix/all/xen-pciback-don-t-allow-msi-x-ops-if-pci_command_mem.patch
bugfix/all/ptrace-being-capable-wrt-a-process-requires-mapped-uids-gids.patch
bugfix/all/keys-fix-race-between-read-and-revoke.patch
bugfix/x86/KVM-x86-Reload-pit-counters-for-all-channels-when-re.patch