fix: check for stack overflow

src/evm.c

@@ -746,24 +746,22 @@ static result_t doCall(context_t *callContext) {
             }
             fprintf(stderr, "op %s\n", opString[op]);
         }
+        #define FAIL_INVALID \
+            callContext->gas = 0; \
+            result.returnData.size = 0; \
+            return result
+        #define OUT_OF_GAS \
+            fprintf(stderr, "Out of gas at pc %" PRIu64 " op %s\n", pc - 1, opString[op]);\
+            FAIL_INVALID
         if (
             (callContext->top < callContext->bottom + argCount[op])
             || (op >= DUP1 && op <= DUP16 && callContext->top - (op - PUSH32) < callContext->bottom)
             || (op >= SWAP1 && op <= SWAP16 && callContext->top - (op - DUP15) < callContext->bottom)
         ) {
             // stack underflow
             fprintf(stderr, "Stack underflow at pc %" PRIu64 " op %s stack depth %lu\n", pc - 1, opString[op], callContext->top - callContext->bottom);
-            callContext->gas = 0;
-            result.returnData.size = 0;
-            return result;
+            FAIL_INVALID;
         }
-        #define FAIL_INVALID \
-            callContext->gas = 0; \
-            result.returnData.size = 0; \
-            return result
-        #define OUT_OF_GAS \
-            fprintf(stderr, "Out of gas at pc %" PRIu64 " op %s\n", pc - 1, opString[op]);\
-            FAIL_INVALID
         // Check staticcall
         switch (op) {
         case CALL:
@@ -794,6 +792,10 @@ static result_t doCall(context_t *callContext) {
         }
         callContext->gas -= gasCost[op];
         callContext->top += retCount[op] - argCount[op];
+        if (callContext->top >= callContext->bottom + 1024) {
+            fprintf(stderr, "Stack overflow at pc %" PRIu64 " op %s stack depth %lu\n", pc - 1, opString[op], callContext->top - callContext->bottom);
+            FAIL_INVALID;
+        }
         switch (op) {
             case PUSH0:
             case PUSH1:

tst/evm.c

@@ -2271,6 +2271,36 @@ void test_returnDataCopyOOB() {
     evmFinalize();
 }
 
+// Each loop iteration nets +1 stack item; the temporary depth peaks at +4 per
+// iteration, hitting 1024 at DUP2 after ~1021 iterations.
+void test_stackOverflow() {
+    evmInit();
+
+    address_t from = AddressFromHex42("0x4a6f6B9fF1fc974096f9063a45Fd12bD5B928AD1");
+    address_t to = AddressFromHex42("0xeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee");
+    val_t value;
+    value[0] = value[1] = value[2] = 0;
+
+    // 0; loop: ADD(1,DUP1); JUMPI(loop, LT(DUP2, 1024))
+    op_t code[] = { PUSH0, JUMPDEST, DUP1, PUSH1, 1, ADD, PUSH2, 4, 0, DUP2, LT, PUSH1, 1, JUMPI };
+    data_t codeData;
+    codeData.content = code;
+    codeData.size = sizeof(code);
+    evmMockCode(to, codeData);
+
+    data_t empty;
+    empty.content = NULL;
+    empty.size = 0;
+    assertStderr(
+        "Stack overflow at pc 9 op DUP2 stack depth 1024\n",
+        result_t result = txCall(from, 0xffffff, to, value, empty, NULL)
+    );
+    assertFailedInvalid(result);
+
+    evmMockCode(to, empty);
+    evmFinalize();
+}
+
 // JUMP to a 0x5b byte that is PUSH1 data → exceptional halt
 void test_jumpDestInsidePush() {
     evmInit();
@@ -2423,6 +2453,7 @@ int main() {
     test_create();
     test_createRevertRollback();
     test_returnDataCopyOOB();
+    test_stackOverflow();
     test_jumpDestInsidePush();
     test_jumpiDestInsidePush();
     test_staticcallSstore();

tst/in/stackoverflow.evm

@@ -0,0 +1,4 @@
+0
+loop:
+ADD(1, DUP1)
+JUMPI(loop, LT(DUP2, 1024))

tst/out/stackoverflow.out

@@ -0,0 +1 @@
+5f5b806001016104008110600157