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authorTom Roeder <tmroeder@google.com>2019-01-24 13:48:20 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-01-31 08:15:42 +0100
commitdcc1097e511f7b66e9beba63443408c86b2f3ee2 (patch)
tree3a5f11cd643092a132b5c9a43fa01832350aa382
parent56b6631bd63b59993295babf2fc12d8cfbc6a07e (diff)
kvm: x86/vmx: Use kzalloc for cached_vmcs12
commit 3a33d030daaa7c507e1c12d5adcf828248429593 upstream. This changes the allocation of cached_vmcs12 to use kzalloc instead of kmalloc. This removes the information leak found by Syzkaller (see Reported-by) in this case and prevents similar leaks from happening based on cached_vmcs12. It also changes vmx_get_nested_state to copy out the full 4k VMCS12_SIZE in copy_to_user rather than only the size of the struct. Tested: rebuilt against head, booted, and ran the syszkaller repro https://syzkaller.appspot.com/text?tag=ReproC&x=174efca3400000 without observing any problems. Reported-by: syzbot+ded1696f6b50b615b630@syzkaller.appspotmail.com Fixes: 8fcc4b5923af5de58b80b53a069453b135693304 Cc: stable@vger.kernel.org Signed-off-by: Tom Roeder <tmroeder@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/kvm/vmx.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 95784bc4a53c..5a2c87552122 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8315,11 +8315,11 @@ static int enter_vmx_operation(struct kvm_vcpu *vcpu)
if (r < 0)
goto out_vmcs02;
- vmx->nested.cached_vmcs12 = kmalloc(VMCS12_SIZE, GFP_KERNEL);
+ vmx->nested.cached_vmcs12 = kzalloc(VMCS12_SIZE, GFP_KERNEL);
if (!vmx->nested.cached_vmcs12)
goto out_cached_vmcs12;
- vmx->nested.cached_shadow_vmcs12 = kmalloc(VMCS12_SIZE, GFP_KERNEL);
+ vmx->nested.cached_shadow_vmcs12 = kzalloc(VMCS12_SIZE, GFP_KERNEL);
if (!vmx->nested.cached_shadow_vmcs12)
goto out_cached_shadow_vmcs12;
@@ -14853,13 +14853,17 @@ static int vmx_get_nested_state(struct kvm_vcpu *vcpu,
copy_shadow_to_vmcs12(vmx);
}
- if (copy_to_user(user_kvm_nested_state->data, vmcs12, sizeof(*vmcs12)))
+ /*
+ * Copy over the full allocated size of vmcs12 rather than just the size
+ * of the struct.
+ */
+ if (copy_to_user(user_kvm_nested_state->data, vmcs12, VMCS12_SIZE))
return -EFAULT;
if (nested_cpu_has_shadow_vmcs(vmcs12) &&
vmcs12->vmcs_link_pointer != -1ull) {
if (copy_to_user(user_kvm_nested_state->data + VMCS12_SIZE,
- get_shadow_vmcs12(vcpu), sizeof(*vmcs12)))
+ get_shadow_vmcs12(vcpu), VMCS12_SIZE))
return -EFAULT;
}