crc32 warning

lib/append_crc32_impl.cc

@@ -24,6 +24,7 @@
 
 #include <cstdint>
 #include <cstring>
+#include <limits>
 #include <stdexcept>
 #include <vector>
 
@@ -75,6 +76,9 @@ void append_crc32_impl::handle(pmt::pmt_t msg)
     result.process_bytes(data, len);
     uint32_t crc = result.checksum();
 
+    if(len > std::numeric_limits<size_t>::max() - sizeof(uint32_t))
+        throw std::length_error("append_crc32 payload too large");
+
     std::vector<uint8_t> out(len + sizeof(uint32_t));
     std::memcpy(out.data(), data, len);
     std::memcpy(out.data() + len, &crc, sizeof(uint32_t));