On Fri, Jun 23, 2017 at 03:58:35AM -0700, Joe Perches wrote:

getsockopt says:

For getsockopt(), optlen is a value-result argument, initially containing the size
of the buffer pointed to by optval, and modified on return to indicate the actual
size of the value returned

In the original code, it's not returning the "actual size of the value
returned". It's returning a smaller or equal value... The man page is
correct that this is how some getsockopts work, of course.  But here
-EFAULT is expected.

regards,
dan carpenter