Fix tableidx overflow on call_indirect (#303)

* Fix maxbits being set to 7 and 1 instead of 32 as described in the spec

* Add FATAL error message when stack size is exceeded when running in DEBUG/TRACE/WARN/INFO mode

This way you get a friendly error when trying to figure out why something is not working instead of a vague segfault.

* Change error message to say "WebAssembly stack overflow"

---------

Co-authored-by: Tom Lauwaerts <[email protected]>

Author: MaartenS11

src/Interpreter/instructions.cpp

@@ -317,7 +317,7 @@ bool i_instr_call(Module *m) {
 bool i_instr_call_indirect(Module *m) {
     uint32_t tidx = read_LEB_32(&m->pc_ptr);  // TODO: use tidx?
     (void)tidx;
-    read_LEB(&m->pc_ptr, 1);  // reserved immediate
+    read_LEB_32(&m->pc_ptr);  // reserved immediate
     uint32_t val = m->stack[m->sp--].value.uint32;
     if (m->options.mangle_table_index) {
         // val is the table address + the index (not sized for the

src/Interpreter/interpreter.cpp

@@ -98,6 +98,12 @@ void Interpreter::setup_call(Module *m, uint32_t fidx) {
     // Push function locals
     for (uint32_t lidx = 0; lidx < func->local_count; lidx++) {
         m->sp += 1;
+#if DEBUG || TRACE || WARN || INFO
+        if (m->sp >= STACK_SIZE) {
+            FATAL("WebAssembly stack overflow m->sp = %d, STACK_SIZE = %d\n",
+                  m->sp, STACK_SIZE);
+        }
+#endif
         m->stack[m->sp].value_type = func->local_value_type[lidx];
         m->stack[m->sp].value = {0};  // Initialize whole union to 0
     }

src/WARDuino/WARDuino.cpp

@@ -159,7 +159,7 @@ void skip_immediates(uint8_t **pos) {
         case 0x11:  // call_indirect
             // encoding: 0x11 x 0x00
             read_LEB_32(pos);  // read x
-            read_LEB(pos, 7);  // 0x00 byte
+            read_LEB_32(pos);  // 0x00 byte
             break;
             // varint64
         case 0x42:  // i64.const