Commit 3921d5b8 authored by Janosch Frank's avatar Janosch Frank Committed by Greg Kroah-Hartman

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: 1e133ab2 ("s390/mm: split arch/s390/mm/pgtable.c")
Signed-off-by: default avatarJanosch Frank <frankja@linux.ibm.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Reported-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Message-Id: <20180816082432.78828-1-frankja@linux.ibm.com>
Signed-off-by: default avatarJanosch Frank <frankja@linux.ibm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 3658ccbb
......@@ -637,6 +637,8 @@ 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);
}
......
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