[compiler-rt] Ensure AsanInitFromRtl is called from a static initializer on OS X by using ASAN_DYNAMIC=1

[kubamracek]

Summary

Hi everyone,

this is an OS X specific patch that adds a dyld initializer (marked with __attribute__((constructor))) which just calls AsanInitFromRtl. The idea is to ensure that the ASan runtime gets initialized early (i.e. before other initializers/constructors) even when DYLD_INSERT_LIBRARIES is not used. In that case, the interceptors are not installed (on OS X, DYLD_INSERT_LIBRARIES is required for interceptors to work), and therefore ASan gets currently initialized quite late -- from the main executable's module initializer. The following issues are a consequence of this:

• https://code.google.com/p/address-sanitizer/issues/detail?id=363
• https://code.google.com/p/address-sanitizer/issues/detail?id=357

Both of them are fixed with this patch.

[ygribov]

There is already code which does precisely this for ASAN_DYNAMIC case in asan_rtl.cc. Could you use it instead? IMHO ASAN_DYNAMIC should be defined on all platforms which use dynamic ASan runtime.

[glider]

lib/asan/asan_mac.cc

70 ↗

(On Diff #18580)

Can you please remind me why do we want to launch without DYLD_INSERT_LIBRARIES?

[kubamracek]

Changing the patch to use ASAN_DYNAMIC=1 on OS X instead. Changing the title of the

Can you please remind me why do we want to launch without DYLD_INSERT_LIBRARIES?

We don't want to launch without DYLD_INSERT_LIBRARIES. Whenever we detect that, we relaunch or abort(). But the cases/issues that this patch solves are crashes that happen even *before* we can detect the missing DYLD_INSERT_LIBRARIES. I'm just trying to initialize ASan even sooner, so we can detect the missing env var sooner.

[ygribov]

Can you implement AsanCheckDynamicRTPrereqs on Mac? This function is supposed to check that dynamic runtime is loaded properly. On Linux this boils down to ensuring that it comes first in dynamic library list. I guess on Darwin we simply need to check DYLD_INSERT_LIBRARIES?

[kubamracek]

In D7117#112336, @ygribov wrote:

Can you implement AsanCheckDynamicRTPrereqs on Mac? This function is supposed to check that dynamic runtime is loaded properly. On Linux this boils down to ensuring that it comes first in dynamic library list. I guess on Darwin we simply need to check DYLD_INSERT_LIBRARIES?

This is already done in asan_mac.cc in MaybeReexec. We could probably get rid of it and move the code to AsanCheckDynamicRTPrereqs instead, but I'd rather do that as a separate patch, since that would be a NFC refactoring, whereas this patch actually changes behavior.

[glider]

test/asan/TestCases/Darwin/mixing-global-constructors.cc

25

This test case has weird indentation. Can you run clang-format just to make sure?

[kubamracek]

Landed in r226929.

lib/asan/CMakeLists.txt

 append_list_if(ANDROID log ASAN_DYNAMIC_LIBS)
 
 # Compile ASan sources into an object library.
 if(APPLE)
   foreach(os ${SANITIZER_COMMON_SUPPORTED_DARWIN_OS})
     add_compiler_rt_darwin_object_library(RTAsan ${os}
       ARCH ${ASAN_SUPPORTED_ARCH}
       SOURCES ${ASAN_SOURCES} ${ASAN_CXX_SOURCES}
-      CFLAGS ${ASAN_CFLAGS}
-      DEFS ${ASAN_COMMON_DEFINITIONS})
+      CFLAGS ${ASAN_DYNAMIC_CFLAGS}
+      DEFS ${ASAN_DYNAMIC_DEFINITIONS})
   endforeach()
 else()
   foreach(arch ${ASAN_SUPPORTED_ARCH})
     add_compiler_rt_object_library(RTAsan ${arch}
       SOURCES ${ASAN_SOURCES} CFLAGS ${ASAN_CFLAGS}
       DEFS ${ASAN_COMMON_DEFINITIONS})
     add_compiler_rt_object_library(RTAsan_cxx ${arch}
       SOURCES ${ASAN_CXX_SOURCES} CFLAGS ${ASAN_CFLAGS}

 if(APPLE)
   foreach (os ${SANITIZER_COMMON_SUPPORTED_DARWIN_OS})
     add_compiler_rt_darwin_dynamic_runtime(clang_rt.asan_${os}_dynamic ${os}
       ARCH ${ASAN_SUPPORTED_ARCH}
       SOURCES $<TARGET_OBJECTS:RTAsan.${os}>
               $<TARGET_OBJECTS:RTInterception.${os}>
               $<TARGET_OBJECTS:RTSanitizerCommon.${os}>
               $<TARGET_OBJECTS:RTLSanCommon.${os}>
-      CFLAGS ${ASAN_CFLAGS}
-      DEFS ${ASAN_COMMON_DEFINITIONS})
+      CFLAGS ${ASAN_DYNAMIC_CFLAGS}
+      DEFS ${ASAN_DYNAMIC_DEFINITIONS})
     add_dependencies(asan clang_rt.asan_${os}_dynamic)
   endforeach()
 else()
   # Build separate libraries for each target.
   foreach(arch ${ASAN_SUPPORTED_ARCH})
     set(ASAN_COMMON_RUNTIME_OBJECTS
       $<TARGET_OBJECTS:RTInterception.${arch}>
       $<TARGET_OBJECTS:RTSanitizerCommon.${arch}>

make/platform/clang_darwin.mk

 CFLAGS.eprintf   := $(CFLAGS) $(OSX_DEPLOYMENT_ARGS)
 CFLAGS.10.4    := $(CFLAGS) $(OSX_DEPLOYMENT_ARGS)
 
 CFLAGS.asan_osx_dynamic := \
  $(CFLAGS) -mmacosx-version-min=10.7 \
  -isysroot $(OSX_SDK) \
  -fno-builtin \
  -gline-tables-only \
- -DMAC_INTERPOSE_FUNCTIONS=1
+ -DMAC_INTERPOSE_FUNCTIONS=1 \
+ -DASAN_DYNAMIC=1
 
 CFLAGS.asan_iossim_dynamic := \
  $(CFLAGS) -mios-simulator-version-min=7.0 \
         -isysroot $(IOSSIM_SDK) \
         -fno-builtin \
  -gline-tables-only \
- -DMAC_INTERPOSE_FUNCTIONS=1
+ -DMAC_INTERPOSE_FUNCTIONS=1 \
+ -DASAN_DYNAMIC=1
 
 CFLAGS.ubsan_osx := $(CFLAGS) -mmacosx-version-min=10.6 \
  -isysroot $(OSX_SDK) \
  -fno-builtin
 
 CFLAGS.ios.i386    := $(CFLAGS) $(IOSSIM_DEPLOYMENT_ARGS)
 CFLAGS.ios.x86_64  := $(CFLAGS) $(IOSSIM_DEPLOYMENT_ARGS)
 CFLAGS.ios.armv7 := $(CFLAGS) $(IOS_DEPLOYMENT_ARGS)

test/asan/TestCases/Darwin/linked-only.cc

+// Main executable is uninstrumented, but linked to ASan runtime.
+// Regression test for https://code.google.com/p/address-sanitizer/issues/detail?id=357.
+
+// RUN: %clangxx -g -O0 %s -c -o %t.o
+// RUN: %clangxx_asan -g -O0 %t.o -o %t
+// RUN: %run %t 2>&1 | FileCheck %s
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "sanitizer/asan_interface.h"
+
+void test_shadow(char *p, size_t size) {
+  fprintf(stderr, "p = %p\n", p);
+  char *q = (char *)__asan_region_is_poisoned(p, size);
+  fprintf(stderr, "=%zd=\n", q ? q - p : -1);
+}
+
+int main(int argc, char *argv[]) {
+  char *p = (char *)malloc(10000);
+  test_shadow(p, 100);
+  free(p);
+  // CHECK: =-1=
+
+  test_shadow((char *)&main, 1);
+  // CHECK: =-1=
+
+  test_shadow((char *)&p, 1);
+  // CHECK: =-1=
+
+  return 0;
+}

test/asan/TestCases/Darwin/mixing-global-constructors.cc

+// A global constructor from a non-instrumented part calls a function
+// in an instrumented part.
+// Regression test for https://code.google.com/p/address-sanitizer/issues/detail?id=363.
+
+// RUN: %clangxx      -DINSTRUMENTED_PART=0 -c %s -o %t-uninst.o
+// RUN: %clangxx_asan -DINSTRUMENTED_PART=1 -c %s -o %t-inst.o
+// RUN: %clangxx_asan %t-uninst.o %t-inst.o -o %t
+
+// RUN: %run %t 2>&1 | FileCheck %s
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+void func(char *ptr);
+
+#if INSTRUMENTED_PART == 1
+
+void func(char *ptr) {
+    *ptr = 'X';
+}
+
+#else // INSTRUMENTED_PART == 1
+
+struct C1 {
+    C1() {
+        printf("Hello ");
+        char buffer[10] = "world";
+        func(buffer);
+        printf("%s\n", buffer);
+    }
+};
+
+C1 *obj = new C1();
+
+int main(int argc, const char * argv[]) {
+    return 0;
+}
+
+#endif // INSTRUMENTED_PART == 1
+
+// CHECK: Hello Xorld