copy_mount_options() problem

["Pavel V. Panteleev" <panteleev_p@xxxxxxx>]

Hello,

copy_mount_options() checks that data doesn't cross TASK_SIZE boundary. 
It's not correct. Really it should check USER_DS boudary, because some 
archs have TASK_SIZE not equal to USER_DS. In this case (USER_DS != 
TASK_SIZE) exact_copy_from_user() will stop on access_ok() check, if 
data cross USER_DS, but doesn't cross TASK_SIZE.

Best regards,
Pavel V. Panteleev