From: Janosch Frank <frankja@xxxxxxxxxx>
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@xxxxxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
CC: stable@xxxxxxxxxxxxxxx # 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);
}
--
2.7.4
