rtppeer: fix UAF when disconnect() triggers self-removal via status_change_event

include/rtpmidid/rtppeer.hpp

@@ -23,6 +23,7 @@
 #include "signal.hpp"
 #include "stats.hpp"
 #include <arpa/inet.h>
+#include <memory>
 #include <string>
 
 namespace rtpmidid {
@@ -41,7 +42,7 @@ class bad_midi_packet : public ::rtpmidid::exception {
       : ::rtpmidid::exception("Bad MIDI packet: {}", what) {}
 };
 
-class rtppeer_t {
+class rtppeer_t : public std::enable_shared_from_this<rtppeer_t> {
   NON_COPYABLE_NOR_MOVABLE(rtppeer_t)
 public:
   // Commands, the id is the same chars as the name

lib/rtppeer.cpp

@@ -858,6 +858,17 @@ void rtppeer_t::parse_journal_chapter_N(uint8_t channel,
   }
 }
 void rtppeer_t::disconnect() {
+  // Keep ourselves alive across send_goodbye(): it fires status_change_event,
+  // whose rtpserverpeer slot calls rtpserver_t::remove_peer(), which erases
+  // the owning rtpserverpeer_t from a vector and drops the last
+  // shared_ptr<rtppeer_t>. Without this local, the reset() below would
+  // run on freed memory.
+  //
+  // weak_from_this().lock() returns nullptr when this instance isn't owned
+  // by a shared_ptr (rtpclient_t embeds rtppeer_t by value; tests construct
+  // it on the stack). In that case no external owner exists to drop us
+  // mid-call, so the UAF can't occur and proceeding without self is safe.
+  auto self = weak_from_this().lock();
   if (status & MIDI_CONNECTED) {
     send_goodbye(MIDI_PORT);
   }