[sanitizer] On OS X, verify that interceptors work and abort if not, take 2

On OS X 10.11+, we have "automatic interceptors", so we don't need to use DYLD_INSERT_LIBRARIES when launching instrumented programs. However, non-instrumented programs that load TSan late (e.g. via dlopen) are currently broken, as TSan will still try to initialize, but the program will crash/hang at random places (because the interceptors don't work). This patch adds an explicit check that interceptors are working, and if not, it aborts and prints out an error message suggesting to explicitly use DYLD_INSERT_LIBRARIES.

TSan unit tests run with a statically linked runtime, where interceptors don't work. To avoid aborting the process in this case, the patch replaces `DisableReexec()` with a weak `ReexecDisabled()` function which is defined to return true in unit tests.

Differential Revision: http://reviews.llvm.org/D18212

llvm-svn: 263695

compiler-rt/lib/asan/tests/asan_noinst_test.cc

@@ -34,7 +34,6 @@
 // Make sure __asan_init is called before any test case is run.
 struct AsanInitCaller {
   AsanInitCaller() {
-    DisableReexec();
     __asan_init();
   }
 };

compiler-rt/lib/asan/tests/asan_test_main.cc

@@ -26,6 +26,12 @@ extern "C" const char* __asan_default_options() {
 #endif
 }
 
+namespace __sanitizer {
+bool ReexecDisabled() {
+  return true;
+}
+}
+
 int main(int argc, char **argv) {
   testing::GTEST_FLAG(death_test_style) = "threadsafe";
   testing::InitGoogleTest(&argc, argv);

compiler-rt/lib/sanitizer_common/sanitizer_common.h

@@ -789,7 +789,6 @@ struct SignalContext {
 
 void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp);
 
-void DisableReexec();
 void MaybeReexec();
 
 template <typename Fn>

compiler-rt/lib/sanitizer_common/sanitizer_linux.cc

@@ -1317,10 +1317,6 @@ void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
 #endif
 }
 
-void DisableReexec() {
-  // No need to re-exec on Linux.
-}
-
 void MaybeReexec() {
   // No need to re-exec on Linux.
 }

compiler-rt/lib/sanitizer_common/sanitizer_mac.cc

@@ -554,10 +554,9 @@ void LeakyResetEnv(const char *name, const char *name_value) {
   }
 }
 
-static bool reexec_disabled = false;
-
-void DisableReexec() {
-  reexec_disabled = true;
+SANITIZER_WEAK_CXX_DEFAULT_IMPL
+bool ReexecDisabled() {
+  return false;
 }
 
 extern "C" double dyldVersionNumber;
@@ -573,7 +572,7 @@ bool DyldNeedsEnvVariable() {
 }
 
 void MaybeReexec() {
-  if (reexec_disabled) return;
+  if (ReexecDisabled()) return;
 
   // Make sure the dynamic runtime library is preloaded so that the
   // wrappers work. If it is not, set DYLD_INSERT_LIBRARIES and re-exec
@@ -627,6 +626,24 @@ void MaybeReexec() {
     CHECK("execv failed" && 0);
   }
 
+  // Verify that interceptors really work.  We'll use dlsym to locate
+  // "pthread_create", if interceptors are working, it should really point to
+  // "wrap_pthread_create" within our own dylib.
+  Dl_info info_pthread_create;
+  void *dlopen_addr = dlsym(RTLD_DEFAULT, "pthread_create");
+  CHECK(dladdr(dlopen_addr, &info_pthread_create));
+  Report("info.dli_fname = %p = %s, info_pthread_create.dli_fname = %p = %s\n",
+         info.dli_fname, info.dli_fname, info_pthread_create.dli_fname,
+         info_pthread_create.dli_fname);
+  if (internal_strcmp(info.dli_fname, info_pthread_create.dli_fname) != 0) {
+    Report(
+        "ERROR: Interceptors are not working. This may be because %s is "
+        "loaded too late (e.g. via dlopen). Please launch the executable "
+        "with:\n%s=%s\n",
+        SanitizerToolName, kDyldInsertLibraries, info.dli_fname);
+    CHECK("interceptors not installed" && 0);
+  }
+
   if (!lib_is_in_env)
     return;
 

compiler-rt/lib/sanitizer_common/sanitizer_win.cc

@@ -842,10 +842,6 @@ void CheckVMASize() {
   // Do nothing.
 }
 
-void DisableReexec() {
-  // No need to re-exec on Windows.
-}
-
 void MaybeReexec() {
   // No need to re-exec on Windows.
 }

compiler-rt/lib/tsan/tests/rtl/tsan_test.cc

@@ -54,6 +54,12 @@ extern "C" const char* __tsan_default_options() {
 }
 #endif
 
+namespace __sanitizer {
+bool ReexecDisabled() {
+  return true;
+}
+}
+
 int main(int argc, char **argv) {
   argv0 = argv[0];
   return run_tests(argc, argv);

compiler-rt/lib/tsan/tests/unit/tsan_unit_test_main.cc

@@ -12,6 +12,12 @@
 //===----------------------------------------------------------------------===//
 #include "gtest/gtest.h"
 
+namespace __sanitizer {
+bool ReexecDisabled() {
+  return true;
+}
+}
+
 int main(int argc, char **argv) {
   testing::GTEST_FLAG(death_test_style) = "threadsafe";
   testing::InitGoogleTest(&argc, argv);

compiler-rt/test/lit.common.cfg

@@ -118,6 +118,14 @@ if config.can_symbolize:
 
 lit.util.usePlatformSdkOnDarwin(config, lit_config)
 
+if config.host_os == 'Darwin':
+  ld_cmd = subprocess.Popen(["bash", "-c", "sw_vers -productVersion | awk -F '.' '{print $1 \".\" $2}'"], stdout = subprocess.PIPE)
+  ld_out = ld_cmd.stdout.read().decode()
+  ld_cmd.wait()
+  osx_version = float(ld_out)
+  if osx_version >= 10.11:
+    config.available_features.add('osx-autointerception')
+
 sancovcc_path = os.path.join(llvm_tools_dir, "sancov") 
 if os.path.exists(sancovcc_path):
   config.available_features.add("has_sancovcc")

compiler-rt/test/tsan/Darwin/dlopen.cc

@@ -0,0 +1,41 @@
+// Checks that on OS X 10.11+ (where we do not re-exec anymore, because
+// interceptors work automatically), dlopen'ing a TSanified library from a
+// non-instrumented program exits with a user-friendly message.
+
+// REQUIRES: osx-autointerception
+
+// RUN: %clangxx_tsan %s -o %t.so -shared -DSHARED_LIB
+// RUN: %clangxx_tsan -fno-sanitize=thread %s -o %t
+
+// RUN: TSAN_DYLIB_PATH=`%clangxx_tsan %s -### 2>&1 \
+// RUN:   | grep "libclang_rt.tsan_osx_dynamic.dylib" \
+// RUN:   | sed -e 's/.*"\(.*libclang_rt.tsan_osx_dynamic.dylib\)".*/\1/'`
+
+// Launching a non-instrumented binary that dlopen's an instrumented library should fail.
+// RUN: not %run %t %t.so 2>&1 | FileCheck %s --check-prefix=CHECK-FAIL
+// Launching a non-instrumented binary with an explicit DYLD_INSERT_LIBRARIES should work.
+// RUN: DYLD_INSERT_LIBRARIES=$TSAN_DYLIB_PATH %run %t %t.so 2>&1 | FileCheck %s
+
+#include <dlfcn.h>
+#include <pthread.h>
+#include <stdio.h>
+
+#if defined(SHARED_LIB)
+extern "C" void foo() {
+  fprintf(stderr, "Hello world.\n");
+}
+#else  // defined(SHARED_LIB)
+int main(int argc, char *argv[]) {
+  void *handle = dlopen(argv[1], RTLD_NOW);
+  fprintf(stderr, "handle = %p\n", handle);
+  void (*foo)() = (void (*)())dlsym(handle, "foo");
+  fprintf(stderr, "foo = %p\n", foo);
+  foo();
+}
+#endif  // defined(SHARED_LIB)
+
+// CHECK: Hello world.
+// CHECK-NOT: ERROR: Interceptors are not working.
+
+// CHECK-FAIL-NOT: Hello world.
+// CHECK-FAIL: ERROR: Interceptors are not working.