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

Marcus Meissner
2011-07-20T11:49:35Z

On Tue, Jul 19, 2011 at 07:38:27PM +0200, Jan Kiszka wrote:
> 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.

I was looking at old code, did not cross check if it is fixed in mainline.

Sorry for the noise.

Ciao, Marcus