Add downstream changes from emscripten (#16)

This includes all downstream changes made so far, including both the
changes carried over from emscripten-libs-19 and the ones that were
added since then. This also includes changes from the newly included
emscripten's `llvm-libc` directory (which is our copy of `libc`).

Author: aheejin

compiler-rt/lib/asan/asan_errors.cpp

@@ -508,6 +508,17 @@ ErrorGeneric::ErrorGeneric(u32 tid, uptr pc_, uptr bp_, uptr sp_, uptr addr,
       scariness.Scare(bug_type_score + read_after_free_bonus, bug_descr);
       if (far_from_bounds) scariness.Scare(10, "far-from-bounds");
     }
+#if SANITIZER_EMSCRIPTEN
+    // If address is in the first page (64 KB), then it is likely that the
+    // access is a result of a null pointer dereference.
+    else if (addr < 65536) {
+      bug_descr = "null-pointer-dereference";
+      scariness.Scare(25, bug_descr);
+    } else if (AddrIsInShadow(addr)) {
+      bug_descr = "shadow-access";
+      scariness.Scare(25, bug_descr);
+    }
+#endif
   }
 }
 

compiler-rt/lib/asan/asan_flags.cpp

@@ -24,6 +24,12 @@
 #include "ubsan/ubsan_flags.h"
 #include "ubsan/ubsan_platform.h"
 
+#if SANITIZER_EMSCRIPTEN
+#include <emscripten/heap.h>
+#include "emscripten_internal.h"
+#endif
+
+
 namespace __asan {
 
 Flags asan_flags_dont_use_directly;  // use via flags().
@@ -70,7 +76,11 @@ static void InitializeDefaultFlags() {
     CommonFlags cf;
     cf.CopyFrom(*common_flags());
     cf.detect_leaks = cf.detect_leaks && CAN_SANITIZE_LEAKS;
+#if !SANITIZER_EMSCRIPTEN
+    // getenv on emscripten uses malloc, which we can't when using LSan.
+    // You can't run external symbolizer executables anyway.
     cf.external_symbolizer_path = GetEnv("ASAN_SYMBOLIZER_PATH");
+#endif
     cf.malloc_context_size = kDefaultMallocContextSize;
     cf.intercept_tls_get_addr = true;
     cf.exitcode = 1;
@@ -129,6 +139,23 @@ static void InitializeDefaultFlags() {
   lsan_parser.ParseString(lsan_default_options);
 #endif
 
+#if SANITIZER_EMSCRIPTEN
+  char *options;
+  // Override from Emscripten Module.
+  // TODO: add EM_ASM_I64 and avoid using a double for a 64-bit pointer.
+#define MAKE_OPTION_LOAD(parser, name) \
+    options = _emscripten_sanitizer_get_option(name); \
+    parser.ParseString(options); \
+    emscripten_builtin_free(options);
+
+  MAKE_OPTION_LOAD(asan_parser, "ASAN_OPTIONS");
+#if CAN_SANITIZE_LEAKS
+  MAKE_OPTION_LOAD(lsan_parser, "LSAN_OPTIONS");
+#endif
+#if CAN_SANITIZE_UB
+  MAKE_OPTION_LOAD(ubsan_parser, "UBSAN_OPTIONS");
+#endif
+#else
   // Override from command line.
   asan_parser.ParseStringFromEnv("ASAN_OPTIONS");
 #if CAN_SANITIZE_LEAKS
@@ -137,9 +164,15 @@ static void InitializeDefaultFlags() {
 #if CAN_SANITIZE_UB
   ubsan_parser.ParseStringFromEnv("UBSAN_OPTIONS");
 #endif
+#endif // SANITIZER_EMSCRIPTEN
 
   InitializeCommonFlags();
 
+#if SANITIZER_EMSCRIPTEN
+  if (common_flags()->malloc_context_size <= 1)
+    StackTrace::snapshot_stack = false;
+#endif // SANITIZER_EMSCRIPTEN
+       //
   // TODO(samsonov): print all of the flags (ASan, LSan, common).
   DisplayHelpMessages(&asan_parser);
 }

compiler-rt/lib/asan/asan_globals.cpp

@@ -387,6 +387,7 @@ void PrintGlobalLocation(InternalScopedString *str, const __asan_global &g,
 // ---------------------- Interface ---------------- {{{1
 using namespace __asan;
 
+#if !SANITIZER_EMSCRIPTEN
 // Apply __asan_register_globals to all globals found in the same loaded
 // executable or shared library as `flag'. The flag tracks whether globals have
 // already been registered or not for this image.
@@ -424,6 +425,7 @@ void __asan_unregister_elf_globals(uptr *flag, void *start, void *stop) {
   __asan_unregister_globals(globals_start, globals_stop - globals_start);
   *flag = 0;
 }
+#endif
 
 // Register an array of globals.
 void __asan_register_globals(__asan_global *globals, uptr n) {

compiler-rt/lib/asan/asan_interceptors.cpp

@@ -27,10 +27,10 @@
 #include "sanitizer_common/sanitizer_internal_defs.h"
 #include "sanitizer_common/sanitizer_libc.h"
 
-// There is no general interception at all on Fuchsia.
+// There is no general interception at all on Fuchsia or Emscripten.
 // Only the functions in asan_interceptors_memintrinsics.cpp are
 // really defined to replace libc functions.
-#if !SANITIZER_FUCHSIA
+#if !SANITIZER_FUCHSIA && !SANITIZER_EMSCRIPTEN
 
 #  if SANITIZER_POSIX
 #    include "sanitizer_common/sanitizer_posix.h"
@@ -911,4 +911,4 @@ void InitializeAsanInterceptors() {
 
 } // namespace __asan
 
-#endif  // !SANITIZER_FUCHSIA
+#endif  // !SANITIZER_FUCHSIA && !SANITIZER_RTEMS && !SANITIZER_EMSCRIPTEN

compiler-rt/lib/asan/asan_interceptors_memintrinsics.cpp

@@ -71,7 +71,7 @@ void *__asan_memmove(void *to, const void *from, uptr size) {
   ASAN_MEMMOVE_IMPL(nullptr, to, from, size);
 }
 
-#if SANITIZER_FUCHSIA
+#if SANITIZER_FUCHSIA || SANITIZER_EMSCRIPTEN
 
 // Fuchsia doesn't use sanitizer_common_interceptors.inc, but
 // the only things there it wants are these three.  Just define them
@@ -81,7 +81,7 @@ extern "C" decltype(__asan_memcpy) memcpy[[gnu::alias("__asan_memcpy")]];
 extern "C" decltype(__asan_memmove) memmove[[gnu::alias("__asan_memmove")]];
 extern "C" decltype(__asan_memset) memset[[gnu::alias("__asan_memset")]];
 
-#else  // SANITIZER_FUCHSIA
+#else  // SANITIZER_FUCHSIA || SANITIZER_EMSCRIPTEN
 
 #define COMMON_INTERCEPTOR_MEMMOVE_IMPL(ctx, to, from, size) \
   do {                                                       \
@@ -103,4 +103,4 @@ extern "C" decltype(__asan_memset) memset[[gnu::alias("__asan_memset")]];
 
 #include "sanitizer_common/sanitizer_common_interceptors_memintrinsics.inc"
 
-#endif  // SANITIZER_FUCHSIA
+#endif  // SANITIZER_FUCHSIA || SANITIZER_EMSCRIPTEN

compiler-rt/lib/asan/asan_malloc_linux.cpp

@@ -15,7 +15,7 @@
 
 #include "sanitizer_common/sanitizer_platform.h"
 #if SANITIZER_FREEBSD || SANITIZER_FUCHSIA || SANITIZER_LINUX || \
-    SANITIZER_NETBSD || SANITIZER_SOLARIS
+    SANITIZER_NETBSD || SANITIZER_SOLARIS || SANITIZER_EMSCRIPTEN
 
 #  include "asan_allocator.h"
 #  include "asan_interceptors.h"

compiler-rt/lib/asan/asan_mapping.h

@@ -272,6 +272,8 @@ extern uptr kHighMemEnd, kMidMemBeg, kMidMemEnd;  // Initialized in __asan_init.
 
 #  if defined(__sparc__) && SANITIZER_WORDSIZE == 64
 #    include "asan_mapping_sparc64.h"
+#  elif SANITIZER_EMSCRIPTEN
+#    include "asan_mapping_emscripten.h"
 #  else
 #    define MEM_TO_SHADOW(mem) \
       (((mem) >> ASAN_SHADOW_SCALE) + (ASAN_SHADOW_OFFSET))

compiler-rt/lib/asan/asan_poisoning.cpp

@@ -175,6 +175,15 @@ uptr __asan_region_is_poisoned(uptr beg, uptr size) {
   if (!size)
     return 0;
   uptr end = beg + size;
+#if SANITIZER_EMSCRIPTEN
+  // XXX Emscripten hack XXX
+  // Null pointer handling, since Emscripten does not crash on null pointer,
+  // ASan must catch null pointer dereference by itself.
+  // Unfortunately, this function returns 0 to mean the region is not
+  // poisoned, so we must return 1 instead if we receive a region
+  // starting at 0.
+  if (!beg) return 1;
+#endif
   if (!AddrIsInMem(beg))
     return beg;
   if (!AddrIsInMem(end))

compiler-rt/lib/asan/asan_poisoning.h

@@ -51,6 +51,10 @@ ALWAYS_INLINE void FastPoisonShadow(uptr aligned_beg, uptr aligned_size,
   // probably provide higher-level interface for these operations.
   // For now, just memset on Windows.
   if (value || SANITIZER_WINDOWS == 1 ||
+      // Emscripten doesn't have a nice way to zero whole pages.
+      // The bulk memory proposal will allow memset to be optimized, but
+      // even then, we still must use memset.
+      SANITIZER_EMSCRIPTEN == 1 ||
       shadow_end - shadow_beg < common_flags()->clear_shadow_mmap_threshold) {
     REAL(memset)((void*)shadow_beg, value, shadow_end - shadow_beg);
   } else {

compiler-rt/lib/asan/asan_posix.cpp

@@ -41,6 +41,9 @@ void AsanOnDeadlySignal(int signo, void *siginfo, void *context) {
 }
 
 bool PlatformUnpoisonStacks() {
+#if SANITIZER_EMSCRIPTEN
+  return false;
+#else
   stack_t signal_stack;
   CHECK_EQ(0, sigaltstack(nullptr, &signal_stack));
   uptr sigalt_bottom = (uptr)signal_stack.ss_sp;
@@ -64,6 +67,7 @@ bool PlatformUnpoisonStacks() {
                        &tls_end);
   UnpoisonStack(stack_begin, stack_end, "default");
   return true;
+#endif
 }
 
 // ---------------------- TSD ---------------- {{{1