OSV-2020-471 Stack-buffer-overflow in ot::Cli::Interpreter::ProcessService

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=12642 Crash type: Stack-buffer-overflow WRITE Crash state: ot::Cli::Interpreter::ProcessService ot::Cli::Interpreter::ProcessLine ot::Cli::Uart::ProcessCommand...