From: Janosch Frank frankja@de.ibm.com

Userspace could have munmapped the area before doing unmapping from the gmap. This would leave us with a valid vmaddr, but an invalid vma from which we would try to zap memory.

Let's check before using the vma.

Fixes: 1e133ab296f3 ("s390/mm: split arch/s390/mm/pgtable.c") Signed-off-by: Janosch Frank frankja@linux.ibm.com Reviewed-by: David Hildenbrand david@redhat.com Reported-by: Dan Carpenter dan.carpenter@oracle.com CC: stable@vger.kernel.org # 4.6+ --- arch/s390/mm/gmap.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c index cb2cd04..b6c85b7 100644 --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -686,6 +686,8 @@ void gmap_discard(struct gmap *gmap, unsigned long from, unsigned long to) vmaddr |= gaddr & ~PMD_MASK; /* Find vma in the parent mm */ vma = find_vma(gmap->mm, vmaddr); + if (!vma) + continue; size = min(to - gaddr, PMD_SIZE - (gaddr & ~PMD_MASK)); zap_page_range(vma, vmaddr, size, NULL); }