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Commit eb0bf929 authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
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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: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 01997bbc

arch/s390/mm/gup.c

+1 −1
Original line number Diff line number Diff line
@@ -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