wasm2c: Add macro and tests to allow disabling stack exhaustion checks

Author: shravanrn

.github/workflows/build.yml

@@ -172,7 +172,7 @@ jobs:
     runs-on: ubuntu-latest
     env:
       USE_NINJA: "1"
-      WASM2C_CFLAGS: "-DWASM_RT_USE_MMAP=1 -DWASM_RT_SKIP_SIGNAL_RECOVERY=1 -DWASM2C_TEST_EMBEDDER_SIGNAL_HANDLING"
+      WASM2C_CFLAGS: "-DWASM_RT_USE_MMAP=1 -DWASM_RT_SKIP_SIGNAL_RECOVERY=1 -DWASM_RT_NONCONFORMING_UNCHECKED_STACK_EXHAUSTION=1 -DWASM2C_TEST_EMBEDDER_SIGNAL_HANDLING"
     steps:
     - uses: actions/setup-python@v1
       with:
@@ -182,5 +182,5 @@ jobs:
         submodules: true
     - run: sudo apt-get install ninja-build
     - run: make clang-debug
-    - name: tests (excluding memory64)
-      run: ./test/run-tests.py --exclude-dir memory64
+    - name: tests (wasm2c tests excluding memory64)
+      run: ./test/run-tests.py wasm2c --exclude-dir memory64

wasm2c/wasm-rt.h

@@ -166,11 +166,20 @@ extern "C" {
 #define WASM_RT_INSTALL_SIGNAL_HANDLER 0
 #endif
 
+/* This macro, if defined, allows the embedder to disable all stack exhaustion
+ * checks. This a non conformant configuration, i.e., this does not respect
+ * Wasm's specification, and may compromise security. Use with caution.
+ */
+#ifndef WASM_RT_NONCONFORMING_UNCHECKED_STACK_EXHAUSTION
+#define WASM_RT_NONCONFORMING_UNCHECKED_STACK_EXHAUSTION 0
+#endif
+
 /* We need to detect and trap stack overflows. If we use a signal handler on
  * POSIX systems, this can detect call stack overflows. On windows, or platforms
  * without a signal handler, we use stack depth counting. */
-#if !defined(WASM_RT_STACK_DEPTH_COUNT) && \
-    !defined(WASM_RT_STACK_EXHAUSTION_HANDLER)
+#if !defined(WASM_RT_STACK_DEPTH_COUNT) &&        \
+    !defined(WASM_RT_STACK_EXHAUSTION_HANDLER) && \
+    !WASM_RT_NONCONFORMING_UNCHECKED_STACK_EXHAUSTION
 
 #if WASM_RT_INSTALL_SIGNAL_HANDLER && !defined(_WIN32)
 #define WASM_RT_STACK_EXHAUSTION_HANDLER 1
@@ -188,6 +197,15 @@ extern "C" {
 #define WASM_RT_STACK_EXHAUSTION_HANDLER 0
 #endif
 
+#if WASM_RT_NONCONFORMING_UNCHECKED_STACK_EXHAUSTION
+
+#if (WASM_RT_STACK_EXHAUSTION_HANDLER + WASM_RT_STACK_DEPTH_COUNT) != 0
+#error \
+    "Cannot specify WASM_RT_NONCONFORMING_UNCHECKED_STACK_EXHAUSTION along with WASM_RT_STACK_EXHAUSTION_HANDLER or WASM_RT_STACK_DEPTH_COUNT"
+#endif
+
+#else
+
 #if (WASM_RT_STACK_EXHAUSTION_HANDLER + WASM_RT_STACK_DEPTH_COUNT) > 1
 #error \
     "Cannot specify multiple options from WASM_RT_STACK_EXHAUSTION_HANDLER , WASM_RT_STACK_DEPTH_COUNT"
@@ -196,6 +214,8 @@ extern "C" {
     "Must specify one of WASM_RT_STACK_EXHAUSTION_HANDLER , WASM_RT_STACK_DEPTH_COUNT"
 #endif
 
+#endif
+
 #if WASM_RT_STACK_EXHAUSTION_HANDLER && !WASM_RT_INSTALL_SIGNAL_HANDLER
 #error \
     "WASM_RT_STACK_EXHAUSTION_HANDLER  can only be used if WASM_RT_INSTALL_SIGNAL_HANDLER is enabled"