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

Juan Quintela
2011-07-19T14:15:14Z

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?

Later, Juan.