s390/gup: handle zero nr_pages case correctly
If [__]get_user_pages_fast() gets called with nr_pages == 0, the current
code would walk the page tables and pin as many pages until the first
invalid pte (or the kernel crashed while writing struct page pointers to
the pages array).
So let's handle at least the nr_pages == 0 case correctly and exit early.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c
index d3a2b81..639fce46 100644
--- a/arch/s390/mm/gup.c
+++ b/arch/s390/mm/gup.c
@@ -180,7 +180,7 @@
addr = start;
len = (unsigned long) nr_pages << PAGE_SHIFT;
end = start + len;
- if ((end < start) || (end > TASK_SIZE))
+ if ((end <= start) || (end > TASK_SIZE))
return 0;
/*
* local_irq_save() doesn't prevent pagetable teardown, but does