Re: [PATCH] kvm: Initialize all struct members to avoid stack information leak

Jan Kiszka
2011-07-19T17:54:42Z

On 2011-07-19 16:12, Juan Quintela wrote:
> Marcus Meissner <meissner@novell.com> wrote:
>> Hi,
>>
>> Reported to us by Stephan Mueller of atsec.
>>
>> Several .pad struct members are not set to something, so they
>> will leak stack content back to user space.
>>
>> Ciao, Marcus
>>
>> Reported-by: Stephan Mueller <smueller@atsec.com>
>> Signed-off-by: Marcus Meissner <meissner@suse.de>
>> ---
>> arch/x86/kvm/x86.c | 1 +
>> 1 files changed, 1 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 77c9d86..621ffb6 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -3002,6 +3002,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
>> case KVM_GET_VCPU_EVENTS: {
>> struct kvm_vcpu_events events;
>>
>> + memset(&events, 0, sizeof(events));
>> kvm_vcpu_ioctl_x86_get_vcpu_events(vcpu, &events);
>>
>> r = -EFAULT;
>
> Looking at arch/x86/include/asm/kvm.h & arch/x86/kvm/x86.c I can't see
> what pad fields are not initialized. My reading is that everything is
> initialized in kvm_vcpu_ioctl_x86_get_vcpu_events(). What field are you
> refering to?

Good question. Information leaks were once addressed by 97e69aa62f, and
kvm_vcpu_events was not changed since then.

Jan

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