Add -s SAFE_STACK to detect stack overflow

emscripten.py

@@ -2291,6 +2291,8 @@ def debug_copy(src, dst):
       cmd.append('--global-base=0')
     else:
       cmd.append('--global-base=%s' % shared.Settings.GLOBAL_BASE)
+  if shared.Settings.SAFE_STACK:
+    cmd.append('--check-stack-overflow')
   shared.print_compiler_stage(cmd)
   stdout = shared.check_call(cmd, stdout=subprocess.PIPE).stdout
   if write_source_map:

src/library.js

@@ -5170,6 +5170,9 @@ LibraryManager.library = {
   },
   // =======================================================================
 
+  __handle_stack_overflow: function() {
+    abort('stack overflow')
+  },
 };
 
 function autoAddDeps(object, name) {

src/postamble.js

@@ -193,6 +193,10 @@ Module['callMain'] = function callMain(args) {
     var start = Date.now();
 #endif
 
+#if SAFE_STACK
+    Module['___set_stack_limit'](STACK_MAX);
+#endif
+
 #if PROXY_TO_PTHREAD
     // User requested the PROXY_TO_PTHREAD option, so call a stub main which pthread_create()s a new thread
     // that will call the user's real main() for the application.

src/settings.js

@@ -242,6 +242,10 @@ var SAFE_HEAP = 0;
 // Log out all SAFE_HEAP operations
 var SAFE_HEAP_LOG = 0;
 
+// Check each stack pointer decrement on WASM backend to ensure that the stack
+// does not overflow.
+var SAFE_STACK = 0;
+
 // In asm.js mode, we cannot simply add function pointers to function tables, so
 // we reserve some slots for them. An alternative to this is to use
 // EMULATED_FUNCTION_POINTERS, in which case we don't need to reserve.

src/worker.js

@@ -239,6 +239,9 @@ this.onmessage = function(e) {
 #if WASM_BACKEND
       Module['_emscripten_tls_init']();
 #endif
+#if SAFE_STACK
+      Module['___set_stack_limit'](STACK_MAX);
+#endif
 #if STACK_OVERFLOW_CHECK
       {{{ makeAsmGlobalAccessInPthread('writeStackCookie') }}}();
 #endif

tests/core/test_safe_stack.c

@@ -0,0 +1,12 @@
+#include <string.h>
+
+int f(int *b) {
+  int a[64];
+  memset(b, 0, 64 * sizeof(int));
+  return f(a);
+}
+
+int main() {
+  int a[64];
+  f(a);
+}

tests/core/test_safe_stack_alloca.c

@@ -0,0 +1,13 @@
+#include <alloca.h>
+#include <string.h>
+#include <stdlib.h>
+
+int f(int *ptr) {
+  for (int i = 0; i < 16384; ++i)
+    ptr[i] = rand();
+  return ptr[16383];
+}
+
+int main() {
+  return f((int*) alloca(65536));
+}

tests/pthread/test_safe_stack.js

@@ -0,0 +1,5 @@
+Module['onAbort'] = function (what) {
+  if (what == 'stack overflow') {
+    reportResultToServer(1);
+  }
+}

tests/runner.py

@@ -291,6 +291,7 @@ def create_test_file(name, contents, binary=False):
   'benchmark',
   'asan',
   'lsan',
+  'wasm2ss',
 ]
 
 test_index = 0

tests/test_browser.py

@@ -3902,6 +3902,11 @@ def test_pthread_tls(self):
   def test_pthread_tls_main(self):
     self.btest(path_from_root('tests', 'pthread', 'test_pthread_tls_main.cpp'), expected='1337', args=['-s', 'USE_PTHREADS', '-std=c++11'])
 
+  @no_fastcomp('-s SAFE_STACK is only supported on WASM backend')
+  @requires_threads
+  def test_pthread_safe_stack(self):
+    self.btest(path_from_root('tests', 'core', 'test_safe_stack.c'), expected='1', args=['-s', 'USE_PTHREADS', '-s', 'PROXY_TO_PTHREAD', '-s', 'SAFE_STACK', '-s', 'DEFAULT_PTHREAD_STACK_SIZE=64KB', '--pre-js', path_from_root('tests', 'pthread', 'test_safe_stack.js')])
+
   @parameterized({
     'leak': ['test_pthread_lsan_leak', ['-g4']],
     'no_leak': ['test_pthread_lsan_no_leak'],

tests/test_core.py

@@ -8039,6 +8039,46 @@ def test_asan_js_stack_op(self):
     self.do_run(open(path_from_root('tests', 'core', 'test_asan_js_stack_op.c')).read(),
                 basename='src.c', expected_output='Hello, World!')
 
+  @no_fastcomp('SAFE_STACK not supported on fastcomp')
+  def test_safe_stack(self):
+    self.set_setting('SAFE_STACK', 1)
+    self.set_setting('TOTAL_STACK', 65536)
+    self.do_run(open(path_from_root('tests', 'core', 'test_safe_stack.c')).read(),
+                expected_output=['abort(stack overflow)', '__handle_stack_overflow'])
+
+  @no_fastcomp('SAFE_STACK not supported on fastcomp')
+  def test_safe_stack_alloca(self):
+    self.set_setting('SAFE_STACK', 1)
+    self.set_setting('TOTAL_STACK', 65536)
+    self.do_run(open(path_from_root('tests', 'core', 'test_safe_stack_alloca.c')).read(),
+                expected_output=['abort(stack overflow)', '__handle_stack_overflow'])
+
+  @needs_dlfcn
+  @no_fastcomp('SAFE_STACK not supported on fastcomp')
+  def test_safe_stack_dylink(self):
+    self.set_setting('SAFE_STACK', 1)
+    self.set_setting('TOTAL_STACK', 65536)
+    self.dylink_test(r'''
+      #include <stdio.h>
+      extern void sidey();
+      int main() {
+        sidey();
+      }
+    ''', '''
+      #include <string.h>
+
+      int f(int *b) {
+        int a[64];
+        memset(b, 0, 2048 * sizeof(int));
+        return f(a);
+      }
+
+      void sidey() {
+        int a[2048];
+        f(a);
+      }
+    ''', ['abort(stack overflow)', '__handle_stack_overflow'])
+
 
 # Generate tests for everything
 def make_run(name, emcc_args, settings=None, env=None):
@@ -8128,6 +8168,7 @@ def setUp(self):
 
 # wasm
 wasm2s = make_run('wasm2s', emcc_args=['-O2'], settings={'SAFE_HEAP': 1})
+wasm2ss = make_run('wasm2ss', emcc_args=['-O2'], settings={'SAFE_STACK': 1})
 
 # emterpreter
 asmi = make_run('asmi', emcc_args=[], settings={'ASM_JS': 2, 'EMTERPRETIFY': 1, 'WASM': 0})