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authorTom Roeder <tmroeder@google.com>2019-01-24 13:48:20 -0800
committerPaolo Bonzini <pbonzini@redhat.com>2019-01-25 18:53:10 +0100
commit3a33d030daaa7c507e1c12d5adcf828248429593 (patch)
treed9b8869868cac17b60e9db17605047669209d28d
parent85ba2b165d11029c0c57a58640d4cf41f9d9fa0d (diff)
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kvm: x86/vmx: Use kzalloc for cached_vmcs12
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>
-rw-r--r--arch/x86/kvm/vmx/nested.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 2616bd2c7f2c..ce8153923854 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4140,11 +4140,11 @@ 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;
@@ -5263,13 +5263,17 @@ 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;
}