The last argument to __skb_header_pointer() should be a buffer large
enough to store struct arphdr. This can be a pointer to a struct arphdr
structure. The code was previously using a pointer to a pointer to
struct arphdr.
By my counting the storage available both before and after is 8 bytes on
x86_64.
Fixes: fa6f2a54d7ac ("flow disector: ARP support") Reported-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org> Signed-off-by: Simon Horman <simon.horman@netronome.com> Signed-off-by: David S. Miller <davem@davemloft.net>