s390/gup: add missing TASK_SIZE check to get_user_pages_fast()
authorHeiko Carstens <heiko.carstens@de.ibm.com>
Mon, 22 Oct 2012 13:49:02 +0000 (15:49 +0200)
committerMartin Schwidefsky <schwidefsky@de.ibm.com>
Tue, 13 Nov 2012 10:02:26 +0000 (11:02 +0100)
commitd55c4c613fc4d4ad2ba0fc6fa2b57176d420f7e4
tree4e28b1a01016e285876876a1c6eb7ba8127f9072
parent658e5ce705f2a09ab681eb61ca7c8619bb7a783d
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>
arch/s390/mm/gup.c