4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Janosch Frank <[email protected]> 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 <[email protected]> Reviewed-by: David Hildenbrand <[email protected]> Reported-by: Dan Carpenter <[email protected]> Message-Id: <[email protected]> Signed-off-by: Janosch Frank <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/s390/mm/pgtable.c | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -637,6 +637,8 @@ void gmap_discard(struct gmap *gmap, uns 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); }
