Avoid UB and abort on nullptr buffer (#7822)

* Avoid UB and abort on nullptr buffer
* Report OOM on return value

Author: paulocsanz

libraries/Netdump/src/Netdump.cpp

@@ -84,19 +84,25 @@ void Netdump::fileDump(File& outfile, const Filter nf)
         fileDumpProcess(outfile, ndp);
     }, nf);
 }
-void Netdump::tcpDump(WiFiServer &tcpDumpServer, const Filter nf)
+bool Netdump::tcpDump(WiFiServer &tcpDumpServer, const Filter nf)
 {
 
     if (!packetBuffer)
     {
         packetBuffer = new (std::nothrow) char[tcpBufferSize];
+
+        if (!packetBuffer)
+        {
+            return false;
+        }
     }
     bufferIndex = 0;
 
     schedule_function([&tcpDumpServer, this, nf]()
     {
         tcpDumpLoop(tcpDumpServer, nf);
     });
+    return true;
 }
 
 void Netdump::capture(int netif_idx, const char* data, size_t len, int out, int success)

libraries/Netdump/src/Netdump.h

@@ -53,7 +53,7 @@ class Netdump
 
     void printDump(Print& out, Packet::PacketDetail ndd, const Filter nf = nullptr);
     void fileDump(File& outfile, const Filter nf = nullptr);
-    void tcpDump(WiFiServer &tcpDumpServer, const Filter nf = nullptr);
+    bool tcpDump(WiFiServer &tcpDumpServer, const Filter nf = nullptr);
 
 
 private: