Commit 516bad44 authored Oct 22, 2012 by Heiko Carstens Committed by Martin Schwidefsky Nov 13, 2012

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 <gerald.schaefer@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

parent d55c4c61

arch/s390/mm/gup.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -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);

Admin message