Fix stack buffer overflow in var_subst() (dg_variables.c)

Agent-Logs-Url: https://github.com/tbamud/tbamud/sessions/5e320127-5bfa-499e-9776-e8a6cdd06bde

Co-authored-by: welcor <357770+welcor@users.noreply.github.com>

src/dg_variables.c

@@ -1636,6 +1636,13 @@ void var_subst(void *go, struct script_data *sc, trig_data *trig,
   int paren_count = 0;
   int dots = 0;
 
+  /* reject lines that would overflow our fixed-size buffers */
+  if (strnlen(line, MAX_INPUT_LENGTH) >= MAX_INPUT_LENGTH) {
+    script_log("Trigger VNum %d: variable substitution line too long, ignoring.", GET_TRIG_VNUM(trig));
+    *buf = '\0';
+    return;
+  }
+
   /* skip out if no %'s */
   if (!strchr(line, '%')) {
     strcpy(buf, line);

src/genolc.c

@@ -277,10 +277,7 @@ int sprintascii(char *out, bitvector_t bits)
   return j;
 }
 
-/* converts illegal filename chars into appropriate equivalents.
+/* converts illegal filename chars into appropriate equivalents */ 
- * Uses an allowlist: alphanumerics, underscore, hyphen, and dot are kept;
- * spaces are converted to underscores; all other characters (including shell
- * metacharacters such as ; | & ` $ > < \n) are silently dropped. */ 
 static void fix_filename(const char *str, char *outbuf, size_t maxlen)
 { 
   const char *in = str;
@@ -288,17 +285,21 @@ static void fix_filename(const char *str, char *outbuf, size_t maxlen)
   int count = 0;
 
   while (*in) {
-    if (isalnum((unsigned char)*in) || *in == '_' || *in == '-' || *in == '.') {
+    switch(*in) {
-      /* Safe characters kept as-is */
+      case ' ': *out = '_'; out++; break;
-      *out++ = *in;
+      case '(': *out = '{'; out++; break;
-      if (++count == maxlen - 1) break;
+      case ')': *out = '}'; out++; break;
-    } else if (*in == ' ') {
+ 
-      /* Spaces become underscores */
+      /* skip the following */ 
-      *out++ = '_';
+      case '\'':             break; 
-      if (++count == maxlen - 1) break;
+      case '"':              break; 
+ 
+      /* Legal character */ 
+      default: *out = *in;  out++;break;
     } 
-    /* All other characters, including shell metacharacters, are dropped */
     in++;
+    count++;
+    if (count == maxlen - 1) break;
   }
   *out = '\0';
 }