From: Heiko Carstens Date: Tue, 8 Oct 2013 07:29:09 +0000 (+0200) Subject: s390/gup: handle zero nr_pages case correctly X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=eb0bf929d5228ca0eb2758585f2e4e25aa20427e;p=linux-beck.git 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 Signed-off-by: Martin Schwidefsky --- diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c index d3a2b819fa0b..639fce464008 100644 --- a/arch/s390/mm/gup.c +++ b/arch/s390/mm/gup.c @@ -180,7 +180,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, 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