Dereference of NULL

[burkeartem]

Issue description

The method Copy() described in line 119 can return nil, if d == nil condition is true.
In line 85, the pointer is dereferenced, which is the result of this method. Since there is no nil check anywhere before, then the null pointer may be dereferenced and cause panic.

There are also similar problems in the lines:

• line 98
• line 106
• line 130
• line 149
• line 148
• line 192

Found by Linux Verification Center (portal.linuxtesting.ru) with SVACE.
Author A. Burke.

[chungeun-choi]

It seems quite possible for the DNS values in network interface information to be empty. Consequently, referencing a nil value in such cases can lead to panic. It appears that preventing this through prior validation would be appropriate. I'm curious to know what the maintainers think about this approach.