Revert "[ASan] Do not misrepresent high value address dereferences as null dereferences"

As it was breaking bots running sanitizer lint check

This reverts r374265 (git b577efe)

llvm-svn: 374308

Author: rgal

compiler-rt/lib/asan/asan_errors.h

@@ -48,8 +48,7 @@ struct ErrorDeadlySignal : ErrorBase {
       scariness.Scare(10, "stack-overflow");
     } else if (!signal.is_memory_access) {
       scariness.Scare(10, "signal");
-    } else if (signal.is_true_faulting_addr &&
-               signal.addr < GetPageSizeCached()) {
+    } else if (signal.addr < GetPageSizeCached()) {
       scariness.Scare(10, "null-deref");
     } else if (signal.addr == signal.pc) {
       scariness.Scare(60, "wild-jump");

compiler-rt/lib/sanitizer_common/sanitizer_common.h

@@ -881,11 +881,6 @@ struct SignalContext {
   bool is_memory_access;
   enum WriteFlag { UNKNOWN, READ, WRITE } write_flag;
 
-  // In some cases the kernel cannot provide the true faulting address; `addr`
-  // will be zero then.  This field allows to distinguish between these cases
-  // and dereferences of null.
-  bool is_true_faulting_addr;
-
   // VS2013 doesn't implement unrestricted unions, so we need a trivial default
   // constructor
   SignalContext() = default;
@@ -898,8 +893,7 @@ struct SignalContext {
         context(context),
         addr(GetAddress()),
         is_memory_access(IsMemoryAccess()),
-        write_flag(GetWriteFlag()),
-        is_true_faulting_addr(IsTrueFaultingAddress()) {
+        write_flag(GetWriteFlag()) {
     InitPcSpBp();
   }
 
@@ -920,7 +914,6 @@ struct SignalContext {
   uptr GetAddress() const;
   WriteFlag GetWriteFlag() const;
   bool IsMemoryAccess() const;
-  bool IsTrueFaultingAddress() const;
 };
 
 void InitializePlatformEarly();

compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

@@ -1849,12 +1849,6 @@ SignalContext::WriteFlag SignalContext::GetWriteFlag() const {
 #endif
 }
 
-bool SignalContext::IsTrueFaultingAddress() const {
-  auto si = static_cast<const siginfo_t *>(siginfo);
-  // SIGSEGV signals without a true fault address have si_code set to 128.
-  return si->si_signo == SIGSEGV && si->si_code != 128;
-}
-
 void SignalContext::DumpAllRegisters(void *context) {
   // FIXME: Implement this.
 }

compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp

@@ -754,12 +754,6 @@ SignalContext::WriteFlag SignalContext::GetWriteFlag() const {
 #endif
 }
 
-bool SignalContext::IsTrueFaultingAddress() const {
-  auto si = static_cast<const siginfo_t *>(siginfo);
-  // "Real" SIGSEGV codes (e.g., SEGV_MAPERR, SEGV_MAPERR) are non-zero.
-  return si->si_signo == SIGSEGV && si->si_code != 0;
-}
-
 static void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
   ucontext_t *ucontext = (ucontext_t*)context;
 # if defined(__aarch64__)

compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_report.cpp

@@ -191,14 +191,9 @@ static void ReportDeadlySignalImpl(const SignalContext &sig, u32 tid,
   SanitizerCommonDecorator d;
   Printf("%s", d.Warning());
   const char *description = sig.Describe();
-  if (sig.is_memory_access && !sig.is_true_faulting_addr)
-    Report("ERROR: %s: %s on unknown address (pc %p bp %p sp %p T%d)\n",
-           SanitizerToolName, description, (void *)sig.pc, (void *)sig.bp,
-           (void *)sig.sp, tid);
-  else
-    Report("ERROR: %s: %s on unknown address %p (pc %p bp %p sp %p T%d)\n",
-           SanitizerToolName, description, (void *)sig.addr, (void *)sig.pc,
-           (void *)sig.bp, (void *)sig.sp, tid);
+  Report("ERROR: %s: %s on unknown address %p (pc %p bp %p sp %p T%d)\n",
+         SanitizerToolName, description, (void *)sig.addr, (void *)sig.pc,
+         (void *)sig.bp, (void *)sig.sp, tid);
   Printf("%s", d.Default());
   if (sig.pc < GetPageSizeCached())
     Report("Hint: pc points to the zero page.\n");
@@ -208,11 +203,7 @@ static void ReportDeadlySignalImpl(const SignalContext &sig, u32 tid,
             ? "WRITE"
             : (sig.write_flag == SignalContext::READ ? "READ" : "UNKNOWN");
     Report("The signal is caused by a %s memory access.\n", access_type);
-    if (!sig.is_true_faulting_addr)
-      Report("Hint: this fault was caused by a dereference of a high value "
-             "address (see registers below).  Dissassemble the provided pc "
-             "to learn which register value was used.\n");
-    else if (sig.addr < GetPageSizeCached())
+    if (sig.addr < GetPageSizeCached())
       Report("Hint: address points to the zero page.\n");
   }
   MaybeReportNonExecRegion(sig.pc);

compiler-rt/lib/sanitizer_common/sanitizer_win.cpp

@@ -945,11 +945,6 @@ bool SignalContext::IsMemoryAccess() const {
   return GetWriteFlag() != SignalContext::UNKNOWN;
 }
 
-bool SignalContext::IsTrueFaultingAddress() const {
-  // TODO: Provide real implementation for this. See Linux and Mac variants.
-  return IsMemoryAccess();
-}
-
 SignalContext::WriteFlag SignalContext::GetWriteFlag() const {
   EXCEPTION_RECORD *exception_record = (EXCEPTION_RECORD *)siginfo;
   // The contents of this array are documented at