Commit 3921d5b8 authored Aug 16, 2018 by Janosch Frank Committed by Greg Kroah-Hartman Dec 01, 2018

s390/mm: Check for valid vma before zapping in gmap_discard



commit 1843abd03250115af6cec0892683e70cf2297c25 upstream.

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>
Message-Id: <20180816082432.78828-1-frankja@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 3658ccbb

arch/s390/mm/pgtable.c

+2 −0

Original line number	Original line	Diff line number	Diff line
	@@ -637,6 +637,8 @@ void gmap_discard(struct gmap *gmap, unsigned long from, unsigned long to)
	vmaddr \|= gaddr & ~PMD_MASK;		vmaddr \|= gaddr & ~PMD_MASK;
	/* Find vma in the parent mm */		/* Find vma in the parent mm */
	vma = find_vma(gmap->mm, vmaddr);		vma = find_vma(gmap->mm, vmaddr);
			if (!vma)
			continue;
	size = min(to - gaddr, PMD_SIZE - (gaddr & ~PMD_MASK));		size = min(to - gaddr, PMD_SIZE - (gaddr & ~PMD_MASK));
	zap_page_range(vma, vmaddr, size, NULL);		zap_page_range(vma, vmaddr, size, NULL);
	}		}