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

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commit d55c4c613f upstream.

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>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This commit is contained in:
Heiko Carstens
2012-10-22 15:49:02 +02:00
committed by Ben Hutchings
parent 8a3a3f4a50
commit 63d0412fb3
1 changed files with 1 additions and 1 deletions
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arch/s390/mm/gup.c
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@ -183,7 +183,7 @@ 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;
/*