Re: [RFC] net/hsr: Add support for IEC 62439-3 High-availability Seamless Redundancy

3) My feeble suggestion to cast icmp_hdr() to (char *) is of course even worse (it doesn't
even avoid the erroneous cast in the first place).

So what do we do?

Reading Documentation/unalgined-memory-access.txt suggests that you
probably should copy the skb before passing up the stack (if necessary).
That is safe (but slightly slower).