fix(firmware): potential crash when using multi protocol module. (#7039)

Co-authored-by: philmoz <phil.a.mitchell@gmail.com>

radio/src/io/multi_protolist.cpp

@@ -162,9 +162,7 @@ std::string MultiRfProtocols::getProtoLabel(unsigned int proto) const
     if (status.protocolName[0] && status.isValid()) {
       return std::string(status.protocolName);
     } else if (proto <= MODULE_SUBTYPE_MULTI_LAST) {
-      char tmp[8];
-      getStringAtIndex(tmp, STR_MULTI_PROTOCOLS, proto);
-      return std::string(tmp);
+      return getStringAtIndex(STR_MULTI_PROTOCOLS, proto);
     }
   } else {
     int idx = getIndex(proto);
@@ -322,8 +320,7 @@ void MultiRfProtocols::fillBuiltinProtos()
 
     if (pdef->protocol == MM_RF_CUSTOM_SELECTED) break;  // skip custom proto
 
-    char tmp[8];
-    rfProto.label = getStringAtIndex(tmp, STR_MULTI_PROTOCOLS, pdef->protocol);
+    rfProto.label = getStringAtIndex(STR_MULTI_PROTOCOLS, pdef->protocol);
     rfProto.flags =
         (pdef->failsafe ? 0x01 : 0) | (pdef->disable_ch_mapping ? 0x02 : 0);
 

radio/src/strhelpers.cpp

@@ -120,6 +120,11 @@ char *strcat_zchar(char *dest, const char *name, uint8_t size,
 #endif
 
 #if !defined(BOOT)
+std::string getStringAtIndex(const char *const *s, int idx)
+{
+  return std::string(s[idx]);
+}
+
 char *getStringAtIndex(char *dest, const char *const *s, int idx)
 {
   strcpy(dest, s[idx]);

radio/src/strhelpers.h

@@ -106,6 +106,7 @@ void formatNumberAsString(char *buffer, const uint8_t buffer_size, int32_t val,
 
 #if !defined(BOOT)
 char *getStringAtIndex(char *dest, const char *const *s, int idx);
+std::string getStringAtIndex(const char *const *s, int idx);
 char *strAppendStringWithIndex(char *dest, const char *s, int idx);
 #define LEN_TIMER_STRING 10  // "-00:00:00"
 char *getTimerString(char *dest, int32_t tme,