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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: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens 2012-10-22 15:49:02 +02:00 committed by Martin Schwidefsky
parent 658e5ce705
commit d55c4c613f
1 changed files with 1 additions and 1 deletions
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2
arch/s390/mm/gup.c
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@ -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;
/*