Description
Null Pointer Dereference in `coap_client_exchange_blockwise2` function in Keith Cullen FreeCoAP 1.0 allows remote attackers to cause a denial of service and potentially execute arbitrary code via a specially crafted CoAP packet that causes `coap_msg_get_payload(resp)` to return a null pointer, which is then dereferenced in a call to `memcpy`.
References
github.com/keith-cullen/FreeCoAP/issues/37
gist.github.com/dqp10515/fe80005e2fb58ed8ada178ac017e4ad4
