[compiler-rt] Prevent symbolizer from starting itself.

[vitalybuka]

Summary

If symbolizer was instrumented with sanitizer and crash, it may
try to call itself again causing infinite recursion of crashing processes.

[eugenis]

It might be better to set ASAN_OPTIONS=symbolize=0 in the environment for the symbolizer process.

[eugenis]

lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc

401

mention "symbolizer" in the warning message

[vitalybuka]

Updated warning message

lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc

: path_(path),
       times_restarted_(0),
       failed_to_start_(false),
       reported_invalid_path_(false),
       use_forkpty_(use_forkpty) {
   CHECK(path_);
   CHECK_NE(path_[0], '\0');
 }
 
+static bool IsSameModule(const char* path) {
+  if (const char* ProcessName = GetProcessName()) {
+    if (const char* SymbolizerName = StripModuleName(path)) {
+      return !internal_strcmp(ProcessName, SymbolizerName);
+    }
+  }
+  return false;
+}
+
 const char *SymbolizerProcess::SendCommand(const char *command) {
+  if (failed_to_start_)
+    return nullptr;
+  if (IsSameModule(path_)) {
+    Report("WARNING: Symbolizer was blocked from starting itself!\n");
+    failed_to_start_ = true;
+    return nullptr;
+  }
   for (; times_restarted_ < kMaxTimesRestarted; times_restarted_++) {
     // Start or restart symbolizer if we failed to send command to it.
     if (const char *res = SendCommandImpl(command))
       return res;
     Restart();
   }
   if (!failed_to_start_) {
     Report("WARNING: Failed to use and restart external symbolizer!\n");