[linux] 01/01: [x86] KVM: Reload pit counters for all channels when restoring state (CVE-2015-7513)

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benh pushed a commit to branch jessie-security
in repository linux.

commit 1a5f283caa851da594447ee2da3239ce5220ca36
Author: Ben Hutchings <ben at decadent.org.uk>
Date:   Fri Jan 1 17:54:42 2016 +0000

    [x86] KVM: Reload pit counters for all channels when restoring state (CVE-2015-7513)
---
 debian/changelog                                   |  2 +
 ...oad-pit-counters-for-all-channels-when-re.patch | 53 ++++++++++++++++++++++
 debian/patches/series                              |  1 +
 3 files changed, 56 insertions(+)

diff --git a/debian/changelog b/debian/changelog
index a1c2e97..a1150d3 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -8,6 +8,8 @@ linux (3.16.7-ckt20-1+deb8u2) UNRELEASED; urgency=medium
   * ptrace: being capable wrt a process requires mapped uids/gids
     (CVE-2015-8709)
   * KEYS: Fix race between read and revoke (CVE-2015-7550)
+  * [x86] KVM: Reload pit counters for all channels when restoring state
+    (CVE-2015-7513)
 
  -- Ben Hutchings <ben at decadent.org.uk>  Sun, 27 Dec 2015 14:20:54 +0000
 
diff --git a/debian/patches/bugfix/x86/KVM-x86-Reload-pit-counters-for-all-channels-when-re.patch b/debian/patches/bugfix/x86/KVM-x86-Reload-pit-counters-for-all-channels-when-re.patch
new file mode 100644
index 0000000..12c2968
--- /dev/null
+++ b/debian/patches/bugfix/x86/KVM-x86-Reload-pit-counters-for-all-channels-when-re.patch
@@ -0,0 +1,53 @@
+From: Andrew Honig <ahonig at 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 at google.com>
+Signed-off-by: Paolo Bonzini <pbonzini at 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
+@@ -3559,10 +3559,11 @@ 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;
+ }
+@@ -3583,6 +3584,7 @@ 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;
+@@ -3592,7 +3594,8 @@ 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;
+ }
diff --git a/debian/patches/series b/debian/patches/series
index 5040f1c..7aae595 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -666,3 +666,4 @@ bugfix/all/bluetooth-validate-socket-address-length-in-sco_sock.patch
 bugfix/all/ptrace-being-capable-wrt-a-process-requires-mapped-uids-gids.patch
 debian/ptrace-fix-abi-change-for-priv-esc-fix.patch
 bugfix/all/keys-fix-race-between-read-and-revoke.patch
+bugfix/x86/KVM-x86-Reload-pit-counters-for-all-channels-when-re.patch

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