On Thu, 21 Dec 2017 10:04:16 +0100
Christian Borntraeger <borntraeger@xxxxxxxxxx> wrote:
> We must not go beyond the pre-allocated buffer. This can happen when
> a new memory slot is added during migration.
>
> Reported-by: David Hildenbrand <david@xxxxxxxxxx>
> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx # 4.13+
> Fixes: 190df4a212a7 (KVM: s390: CMMA tracking, ESSA emulation, migration mode)
> ---
> arch/s390/kvm/priv.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
> index c954ac49eee4..3211bf58d838 100644
> --- a/arch/s390/kvm/priv.c
> +++ b/arch/s390/kvm/priv.c
> @@ -1002,7 +1002,7 @@ static inline int do_essa(struct kvm_vcpu *vcpu, const int orc)
> cbrlo[entries] = gfn << PAGE_SHIFT;
> }
>
> - if (orc) {
> + if (orc && gfn < ms->bitmap_size) {
> /* increment only if we are really flipping the bit to 1 */
> if (!test_and_set_bit(gfn, ms->pgste_bitmap))
> atomic64_inc(&ms->dirty_pages);
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
