Re: [PATCH v2] powerpc: kvm: powerpc: fix information leak to userland

[Alexander Graf <agraf@suse.de>]

On 30.10.2010, at 11:55, Vasiliy Kulikov wrote:

> Structure kvm_ppc_pvinfo is copied to userland with "flags" and "pad"
> fields unitialized.  It leads to leaking of contents of kernel stack
> memory.  We have to initialize them to zero.
>=20
> In patch v1 Jan Kiszka suggested to fill reserved fields with zeros
> instead of memset'ting the whole struct.  It makes sense as these
> fields are explicitly marked as padding.  No more fields need zeroing.
>=20
> Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
> ---
> arch/powerpc/kvm/powerpc.c |    2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>=20
> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> index 2f87a16..5962336 100644
> --- a/arch/powerpc/kvm/powerpc.c
> +++ b/arch/powerpc/kvm/powerpc.c
> @@ -604,6 +604,8 @@ static int kvm_vm_ioctl_get_pvinfo(struct =
kvm_ppc_pvinfo *pvinfo)
> 	pvinfo->hcall[1] =3D inst_ori | (KVM_SC_MAGIC_R0 & =
inst_imm_mask);
> 	pvinfo->hcall[2] =3D inst_sc;
> 	pvinfo->hcall[3] =3D inst_nop;
> +	pvinfo->flags =3D 0;
> +	memset(&pvinfo->pad, 0, sizeof(pvinfo->pad));

This should only be memset(pvinfo->pad), no? It's an array after all =
which automatically translates to a pointer when referenced.

Alex