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Commit d55c4c61 authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
Browse files

s390/gup: add missing TASK_SIZE check to get_user_pages_fast() 



When walking page tables we need to make sure that everything
is within bounds of the ASCE limit of the task's address space.
Otherwise we might calculate e.g. a pud pointer which is not
within a pud and dereference it.
So check against TASK_SIZE (which is the ASCE limit) before
walking page tables.

Reviewed-by: default avatarGerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 658e5ce7

arch/s390/mm/gup.c

+1 −1
Original line number Diff line number Diff line
@@ -229,7 +229,7 @@ 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)

	if ((end < start) || (end > TASK_SIZE))

		goto slow_irqon;



	/*