From 516bad44b9f3bdcb0be6be0252b7557bf7a149e4 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 22 Oct 2012 15:58:26 +0200 Subject: [PATCH] s390/gup: fix access_ok() usage in __get_user_pages_fast() access_ok() returns always "true" on s390. Therefore all access_ok() invocations are rather pointless. However when walking page tables we need to make sure that everything is within bounds of the ASCE limit of the task's address space. So remove the access_ok() call and add the same check we have in get_user_pages_fast(). Reviewed-by: Gerald Schaefer Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/mm/gup.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c index 16fb3c1615dc..1f5315d1215c 100644 --- a/arch/s390/mm/gup.c +++ b/arch/s390/mm/gup.c @@ -180,8 +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 (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ, - (void __user *)start, len))) + if ((end < start) || (end > TASK_SIZE)) return 0; local_irq_save(flags); -- 2.20.1