Provided by: linux-doc-2.6.15_2.6.15-23.39_all bug


       access_ok - Checks if a user space pointer is valid


       access_ok  (type, addr, size);


       type   Type   of   access:   VERIFY_READ  or  VERIFY_WRITE.  Note  that
              VERIFY_WRITE is a superset of VERIFY_READ - if  it  is  safe  to
              write to a block, it is always safe to read from it.

       addr   User space pointer to start of block to check

       size   Size of block to check


       User context only. This function may sleep.


       Checks if a pointer to a block of memory in user space is valid.

       Returns  true  (nonzero) if the memory block may be valid, false (zero)
       if it is definitely invalid.

       Note that, depending  on  architecture,  this  function  probably  just
       checks that the pointer is in the user space range - after calling this
       function, memory access functions may still return -EFAULT.