Revert "[sanitizer] Add cloak_sanitizer_signal_handlers runtime option"

compiler-rt/lib/sanitizer_common/sanitizer_common.h

@@ -390,9 +390,6 @@ void ReportDeadlySignal(const SignalContext &sig, u32 tid,
 void SetAlternateSignalStack();
 void UnsetAlternateSignalStack();
 
-bool IsSignalHandlerFromSanitizer(int signum);
-bool SetSignalHandlerFromSanitizer(int signum, bool new_state);
-
 // Construct a one-line string:
 //   SUMMARY: SanitizerToolName: error_message
 // and pass it to __sanitizer_report_error_summary.

compiler-rt/lib/sanitizer_common/sanitizer_flags.inc

@@ -113,11 +113,6 @@ COMMON_FLAG(HandleSignalMode, handle_sigfpe, kHandleSignalYes,
 COMMON_FLAG(bool, allow_user_segv_handler, true,
             "Deprecated. True has no effect, use handle_sigbus=1. If false, "
             "handle_*=1 will be upgraded to handle_*=2.")
-COMMON_FLAG(bool, cloak_sanitizer_signal_handlers, false,
-            "If set, signal/sigaction will pretend that sanitizers did not "
-            "preinstall any signal handlers. If the user subsequently installs "
-            "a signal handler, this will disable cloaking for the respective "
-            "signal.")
 COMMON_FLAG(bool, use_sigaltstack, true,
             "If set, uses alternate stack for signal handling.")
 COMMON_FLAG(bool, detect_deadlocks, true,

compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cpp

@@ -47,8 +47,6 @@ typedef void (*sa_sigaction_t)(int, siginfo_t *, void *);
 
 namespace __sanitizer {
 
-static atomic_uint8_t signal_handler_is_from_sanitizer[64];
-
 u32 GetUid() {
   return getuid();
 }
@@ -212,20 +210,6 @@ void UnsetAlternateSignalStack() {
   UnmapOrDie(oldstack.ss_sp, oldstack.ss_size);
 }
 
-bool IsSignalHandlerFromSanitizer(int signum) {
-  return atomic_load(&signal_handler_is_from_sanitizer[signum],
-                     memory_order_relaxed);
-}
-
-bool SetSignalHandlerFromSanitizer(int signum, bool new_state) {
-  if (signum < 0 || static_cast<unsigned>(signum) >=
-                        ARRAY_SIZE(signal_handler_is_from_sanitizer))
-    return false;
-
-  return atomic_exchange(&signal_handler_is_from_sanitizer[signum], new_state,
-                         memory_order_relaxed);
-}
-
 static void MaybeInstallSigaction(int signum,
                                   SignalHandlerType handler) {
   if (GetHandleSignalMode(signum) == kHandleSignalNo) return;
@@ -239,9 +223,6 @@ static void MaybeInstallSigaction(int signum,
   if (common_flags()->use_sigaltstack) sigact.sa_flags |= SA_ONSTACK;
   CHECK_EQ(0, internal_sigaction(signum, &sigact, nullptr));
   VReport(1, "Installed the sigaction for signal %d\n", signum);
-
-  if (common_flags()->cloak_sanitizer_signal_handlers)
-    SetSignalHandlerFromSanitizer(signum, true);
 }
 
 void InstallDeadlySignalHandlers(SignalHandlerType handler) {

compiler-rt/lib/sanitizer_common/sanitizer_signal_interceptors.inc

@@ -45,8 +45,6 @@ using namespace __sanitizer;
 INTERCEPTOR(uptr, bsd_signal, int signum, uptr handler) {
   SIGNAL_INTERCEPTOR_ENTER();
   if (GetHandleSignalMode(signum) == kHandleSignalExclusive) return 0;
-
-  // TODO: support cloak_sanitizer_signal_handlers
   SIGNAL_INTERCEPTOR_SIGNAL_IMPL(bsd_signal, signum, handler);
 }
 #define INIT_BSD_SIGNAL COMMON_INTERCEPT_FUNCTION(bsd_signal)
@@ -58,55 +56,19 @@ INTERCEPTOR(uptr, bsd_signal, int signum, uptr handler) {
 INTERCEPTOR(uptr, signal, int signum, uptr handler) {
   SIGNAL_INTERCEPTOR_ENTER();
   if (GetHandleSignalMode(signum) == kHandleSignalExclusive)
-    // The user can neither view nor change the signal handler, regardless of
-    // the cloak_sanitizer_signal_handlers setting. This differs from
-    // sigaction().
     return (uptr) nullptr;
-
-  uptr ret = +[](auto signal, int signum, uptr handler) {
-    SIGNAL_INTERCEPTOR_SIGNAL_IMPL(signal, signum, handler);
-  }(signal, signum, handler);
-
-  if (ret != sig_err && SetSignalHandlerFromSanitizer(signum, false))
-    // If the user sets a signal handler, it becomes uncloaked, even if they
-    // reuse a sanitizer's signal handler.
-    ret = sig_dfl;
-
-  return ret;
+  SIGNAL_INTERCEPTOR_SIGNAL_IMPL(signal, signum, handler);
 }
 #define INIT_SIGNAL COMMON_INTERCEPT_FUNCTION(signal)
 
 INTERCEPTOR(int, sigaction_symname, int signum,
             const __sanitizer_sigaction *act, __sanitizer_sigaction *oldact) {
   SIGNAL_INTERCEPTOR_ENTER();
-
   if (GetHandleSignalMode(signum) == kHandleSignalExclusive) {
     if (!oldact) return 0;
     act = nullptr;
-    // If cloak_sanitizer_signal_handlers=true, the user can neither view nor
-    // change the signal handle.
-    // If false, the user can view but not change the signal handler. This
-    // differs from signal().
   }
-
-  int ret = +[](int signum, const __sanitizer_sigaction* act,
-                __sanitizer_sigaction* oldact) {
-    SIGNAL_INTERCEPTOR_SIGACTION_IMPL(signum, act, oldact);
-  }(signum, act, oldact);
-
-  if (act) {
-    if (ret == 0 && SetSignalHandlerFromSanitizer(signum, false)) {
-      // If the user sets a signal handler, it becomes uncloaked, even if they
-      // reuse a sanitizer's signal handler.
-
-      if (oldact)
-        oldact->handler = reinterpret_cast<__sanitizer_sighandler_ptr>(sig_dfl);
-    }
-  } else if (ret == 0 && oldact && IsSignalHandlerFromSanitizer(signum)) {
-    oldact->handler = reinterpret_cast<__sanitizer_sighandler_ptr>(sig_dfl);
-  }
-
-  return ret;
+  SIGNAL_INTERCEPTOR_SIGACTION_IMPL(signum, act, oldact);
 }
 #define INIT_SIGACTION COMMON_INTERCEPT_FUNCTION(sigaction_symname)
 

compiler-rt/test/sanitizer_common/TestCases/Linux/allow_user_segv.cpp

@@ -23,10 +23,6 @@
 // Flaky errors in debuggerd with "waitpid returned unexpected pid (0)" in logcat.
 // UNSUPPORTED: android && i386-target-arch
 
-// Note: this test case is unusual because it retrieves the original
-// (ASan-installed) signal handler; thus, it is incompatible with the
-// cloak_sanitizer_signal_handlers runtime option.
-
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>