Stop tracking atexit/__cxa_atexit/pthread_atfork allocations in LSan/NetBSD

[krytarowski]

Summary

The atexit(3) and __cxa_atexit() calls allocate internally memory and free on exit,
after executing all callback. This causes false positives as DoLeakCheck() is called
from the atexit handler. In the LSan/ASan tests there are strict checks triggering
false positives here.

Intercept all atexit(3) and __cxa_atexit() calls and disable LSan when calling the
real functions.

Stop tracing allocations in pthread_atfork(3) funtions, as there are performed
internal allocations that are not freed for the time of running StopTheWorld()
code. This avoids false-positives.

The same changes have to be replicated in the ASan and LSan runtime.

Non-NetBSD OSs are not tested and this code is restricted to NetBSD only.

[vitalybuka]

lib/asan/asan_interceptors.cpp

591

ASAN_INTERCEPT_ATEXIT ?

605

ASAN_INTERCEPT_.... ?

lib/lsan/lsan_interceptors.cpp

349

why only NETBSD in lsan for __cxa_atexit

[krytarowski]

• apply changes from review

[krytarowski]

lib/lsan/lsan_interceptors.cpp

349

!NetBSD not tested. Feel free to test it and enable it once the change will land.

[vitalybuka]

Tests?

[krytarowski]

In D67331#1677564, @vitalybuka wrote:

Tests?

Actually these problems are triggered by the existing tests and any other real non-trivial application used with LSan/NetBSD.

[krytarowski]

With these patches included there are still ~3 failing tests and I will mark them as XFAIL for now.

LSan/Linux tests can be reused on NetBSD almost fully, but I will keep it for another iteration.

[uweigand]

This commit causes test failures (at least) on the SystemZ build bots:

[7/99] Running lint check for sanitizer sources...
FAILED: projects/compiler-rt/lib/CMakeFiles/SanitizerLintCheck 
[...]
/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/projects/compiler-rt/lib/lsan/lsan_interceptors.cpp:378:  Lines should be <= 80 characters long  [whitespace/line_length] [2]
/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/projects/compiler-rt/lib/asan/asan_interceptors.cpp:610:  Lines should be <= 80 characters long  [whitespace/line_length] [2]

[jsji]

In D67331#1677773, @uweigand wrote:

This commit causes test failures (at least) on the SystemZ build bots:

[7/99] Running lint check for sanitizer sources...
FAILED: projects/compiler-rt/lib/CMakeFiles/SanitizerLintCheck 
[...]
/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/projects/compiler-rt/lib/lsan/lsan_interceptors.cpp:378:  Lines should be <= 80 characters long  [whitespace/line_length] [2]
/home/uweigand/sandbox/buildbot/clang-s390x-linux/llvm/projects/compiler-rt/lib/asan/asan_interceptors.cpp:610:  Lines should be <= 80 characters long  [whitespace/line_length] [2]

Also failed on PowerPC. Should be fixed with https://reviews.llvm.org/rL372511.

lib/asan/asan_interceptors.h

 #endif
 
 #if !SANITIZER_WINDOWS
 # define ASAN_INTERCEPT___CXA_ATEXIT 1
 #else
 # define ASAN_INTERCEPT___CXA_ATEXIT 0
 #endif
 
+#if SANITIZER_NETBSD
+# define ASAN_INTERCEPT_ATEXIT 1
+#else
+# define ASAN_INTERCEPT_ATEXIT 0
+#endif
+
 #if SANITIZER_LINUX && !SANITIZER_ANDROID
 # define ASAN_INTERCEPT___STRDUP 1
 #else
 # define ASAN_INTERCEPT___STRDUP 0
 #endif
 
 #if SANITIZER_LINUX && (defined(__arm__) || defined(__aarch64__) || \
                         defined(__i386__) || defined(__x86_64__))
 # define ASAN_INTERCEPT_VFORK 1
 #else
 # define ASAN_INTERCEPT_VFORK 0
 #endif
 
+#if SANITIZER_NETBSD
+# define ASAN_INTERCEPT_PTHREAD_ATFORK 1
+#else
+# define ASAN_INTERCEPT_PTHREAD_ATFORK 0
+#endif
+
 DECLARE_REAL(int, memcmp, const void *a1, const void *a2, uptr size)
 DECLARE_REAL(char*, strchr, const char *str, int c)
 DECLARE_REAL(SIZE_T, strlen, const char *s)
 DECLARE_REAL(char*, strncpy, char *to, const char *from, uptr size)
 DECLARE_REAL(uptr, strnlen, const char *s, uptr maxlen)
 DECLARE_REAL(char*, strstr, const char *s1, const char *s2)
 
 #if !SANITIZER_MAC

lib/asan/asan_interceptors.cpp

INTERCEPTOR(long long, atoll, const char *nptr) {
   char *real_endptr;
   long long result = REAL(strtoll)(nptr, &real_endptr, 10);
   FixRealStrtolEndptr(nptr, &real_endptr);
   ASAN_READ_STRING(ctx, nptr, (real_endptr - nptr) + 1);
   return result;
 }
 #endif  // ASAN_INTERCEPT_ATOLL_AND_STRTOLL
 
-#if ASAN_INTERCEPT___CXA_ATEXIT
+#if ASAN_INTERCEPT___CXA_ATEXIT || ASAN_INTERCEPT_ATEXIT
 static void AtCxaAtexit(void *unused) {
   (void)unused;
   StopInitOrderChecking();
 }
+#endif
 
+#if ASAN_INTERCEPT___CXA_ATEXIT
 INTERCEPTOR(int, __cxa_atexit, void (*func)(void *), void *arg,
             void *dso_handle) {
 #if SANITIZER_MAC
   if (UNLIKELY(!asan_inited)) return REAL(__cxa_atexit)(func, arg, dso_handle);
 #endif
   ENSURE_ASAN_INITED();
+#if CAN_SANITIZE_LEAKS
+  __lsan::ScopedInterceptorDisabler disabler;
+#endif
   int res = REAL(__cxa_atexit)(func, arg, dso_handle);
   REAL(__cxa_atexit)(AtCxaAtexit, nullptr, nullptr);
   return res;
 }
 #endif  // ASAN_INTERCEPT___CXA_ATEXIT
 
+#if ASAN_INTERCEPT_ATEXIT
+INTERCEPTOR(int, atexit, void (*func)()) {
+  ENSURE_ASAN_INITED();
+#if CAN_SANITIZE_LEAKS
+  __lsan::ScopedInterceptorDisabler disabler;
+#endif
+  // Avoid calling real atexit as it is unrechable on at least on Linux.
+  int res = REAL(__cxa_atexit)((void (*)(void *a))func, nullptr, nullptr);
+  REAL(__cxa_atexit)(AtCxaAtexit, nullptr, nullptr);
+  return res;
+}
+#endif
+
+#if ASAN_INTERCEPT_PTHREAD_ATFORK
+extern "C" {
+extern int _pthread_atfork(void (*prepare)(), void (*parent)(),
+                           void (*child)());
+};
+
+INTERCEPTOR(int, pthread_atfork, void (*prepare)(), void (*parent)(),
+            void (*child)()) {
+#if CAN_SANITIZE_LEAKS
+  __lsan::ScopedInterceptorDisabler disabler;
+#endif
+  // REAL(pthread_atfork) cannot be called due to symbol indirections at least on NetBSD
+  return _pthread_atfork(prepare, parent, child);
+}
+#endif
+
 #if ASAN_INTERCEPT_VFORK
 DEFINE_REAL(int, vfork)
 DECLARE_EXTERN_INTERCEPTOR_AND_WRAPPER(int, vfork)
 #endif
 
 // ---------------------- InitializeAsanInterceptors ---------------- {{{1
 namespace __asan {
 void InitializeAsanInterceptors() {
#endif
   ASAN_INTERCEPT_FUNC(pthread_join);
 #endif
 
   // Intercept atexit function.
 #if ASAN_INTERCEPT___CXA_ATEXIT
   ASAN_INTERCEPT_FUNC(__cxa_atexit);
 #endif
 
+#if ASAN_INTERCEPT_ATEXIT
+  ASAN_INTERCEPT_FUNC(atexit);
+#endif
+
+#if ASAN_INTERCEPT_PTHREAD_ATFORK
+  ASAN_INTERCEPT_FUNC(pthread_atfork);
+#endif
+
 #if ASAN_INTERCEPT_VFORK
   ASAN_INTERCEPT_FUNC(vfork);
 #endif
 
   InitializePlatformInterceptors();
 
   VReport(1, "AddressSanitizer: libc interceptors initialized\n");
 }
 
 } // namespace __asan
 
 #endif  // !SANITIZER_FUCHSIA

lib/lsan/lsan_interceptors.cpp

INTERCEPTOR(void, thr_exit, tid_t *state) {
   REAL(thr_exit)(state);
 }
 #define LSAN_MAYBE_INTERCEPT_THR_EXIT INTERCEPT_FUNCTION(thr_exit)
 #else
 #define LSAN_MAYBE_INTERCEPT_THR_EXIT
 #endif
 
 #if SANITIZER_INTERCEPT_STRERROR
 INTERCEPTOR(char *, strerror, int errnum) {
   __lsan::ScopedInterceptorDisabler disabler;
   return REAL(strerror)(errnum);
 }
 #define LSAN_MAYBE_INTERCEPT_STRERROR INTERCEPT_FUNCTION(strerror)
 #else
 #define LSAN_MAYBE_INTERCEPT_STRERROR
 #endif
 
+#if SANITIZER_INTERCEPT___CXA_ATEXIT
+INTERCEPTOR(int, __cxa_atexit, void (*func)(void *), void *arg,
+            void *dso_handle) {
+  __lsan::ScopedInterceptorDisabler disabler;
+  return REAL(__cxa_atexit)(func, arg, dso_handle);
+}
+#define LSAN_MAYBE_INTERCEPT___CXA_ATEXIT INTERCEPT_FUNCTION(__cxa_atexit)
+#else
+#define LSAN_MAYBE_INTERCEPT___CXA_ATEXIT
+#endif
+
+#if SANITIZER_INTERCEPT_ATEXIT
+INTERCEPTOR(int, atexit, void (*f)()) {
+  __lsan::ScopedInterceptorDisabler disabler;
+  return REAL(__cxa_atexit)((void (*)(void *a))f, 0, 0);
+}
+#define LSAN_MAYBE_INTERCEPT_ATEXIT INTERCEPT_FUNCTION(atexit)
+#else
+#define LSAN_MAYBE_INTERCEPT_ATEXIT
+#endif
+
+#if SANITIZER_INTERCEPT_PTHREAD_ATFORK
+extern "C" {
+extern int _pthread_atfork(void (*prepare)(), void (*parent)(),
+                           void (*child)());
+};
+
+INTERCEPTOR(int, pthread_atfork, void (*prepare)(), void (*parent)(),
+            void (*child)()) {
+  __lsan::ScopedInterceptorDisabler disabler;
+  // REAL(pthread_atfork) cannot be called due to symbol indirections at least on NetBSD
+  return _pthread_atfork(prepare, parent, child);
+}
+#define LSAN_MAYBE_INTERCEPT_PTHREAD_ATFORK INTERCEPT_FUNCTION(pthread_atfork)
+#else
+#define LSAN_MAYBE_INTERCEPT_PTHREAD_ATFORK
+#endif
+
 struct ThreadParam {
   void *(*callback)(void *arg);
   void *param;
   atomic_uintptr_t tid;
 };
 
 extern "C" void *__lsan_thread_start_func(void *arg) {
   ThreadParam *p = (ThreadParam*)arg;
void InitializeInterceptors() {
   INTERCEPT_FUNCTION(pthread_join);
   INTERCEPT_FUNCTION(_exit);
 
   LSAN_MAYBE_INTERCEPT__LWP_EXIT;
   LSAN_MAYBE_INTERCEPT_THR_EXIT;
 
   LSAN_MAYBE_INTERCEPT_STRERROR;
 
+  LSAN_MAYBE_INTERCEPT___CXA_ATEXIT;
+  LSAN_MAYBE_INTERCEPT_ATEXIT;
+  LSAN_MAYBE_INTERCEPT_PTHREAD_ATFORK;
+
 #if !SANITIZER_NETBSD && !SANITIZER_FREEBSD
   if (pthread_key_create(&g_thread_finalize_key, &thread_finalize)) {
     Report("LeakSanitizer: failed to create thread key.\n");
     Die();
   }
 #endif
 }
 
 } // namespace __lsan

lib/sanitizer_common/sanitizer_platform_interceptors.h

 #define SANITIZER_INTERCEPT_FUNOPEN2 SI_NETBSD
 #define SANITIZER_INTERCEPT_GETFSENT (SI_FREEBSD || SI_NETBSD || SI_MAC)
 #define SANITIZER_INTERCEPT_ARC4RANDOM (SI_FREEBSD || SI_NETBSD || SI_MAC)
 #define SANITIZER_INTERCEPT_FDEVNAME SI_FREEBSD
 #define SANITIZER_INTERCEPT_GETUSERSHELL (SI_POSIX && !SI_ANDROID)
 #define SANITIZER_INTERCEPT_SL_INIT (SI_FREEBSD || SI_NETBSD)
 
 #define SANITIZER_INTERCEPT_GETRANDOM SI_LINUX
+#define SANITIZER_INTERCEPT___CXA_ATEXIT SI_NETBSD
+#define SANITIZER_INTERCEPT_ATEXIT SI_NETBSD
+#define SANITIZER_INTERCEPT_PTHREAD_ATFORK SI_NETBSD
+
 
 #endif  // #ifndef SANITIZER_PLATFORM_INTERCEPTORS_H