[PATCH] [asan] Prevent __attribute__((annotate)) triggering errors on Darwin

[Anna Zaks]

Hi kubabrecka, samsonov,


    The following code triggers a fatal error in the compiler instrumentation
    of ASan on Darwin because we place the attribute into llvm.metadata section,
    which does not have the proper MachO section name.
    
    void foo() __attribute__((annotate("custom")));
    void foo() {;}
    
    This commit reorders the checks so that we skip everything in llvm.metadata
    first. It also removes the hard failure in case the section name does not
    parse. That check will be done lower in the compilation pipeline anyway.

http://reviews.llvm.org/D9093

Files:
  lib/Transforms/Instrumentation/AddressSanitizer.cpp
  test/Instrumentation/AddressSanitizer/do-not-instrument-llvm-metadata-darwin.ll

Index: lib/Transforms/Instrumentation/AddressSanitizer.cpp
===================================================================
--- lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -1158,15 +1158,27 @@
   if (G->hasSection()) {
     StringRef Section(G->getSection());
 
+    // Globals from llvm.metadata aren't emitted, do not instrument them.
+    if (Section == "llvm.metadata") return false;
+
+    // Callbacks put into the CRT initializer/terminator sections
+    // should not be instrumented.
+    // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
+    // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
+    if (Section.startswith(".CRT")) {
+      DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
+      return false;
+    }
+
     if (TargetTriple.isOSBinFormatMachO()) {
       StringRef ParsedSegment, ParsedSection;
       unsigned TAA = 0, StubSize = 0;
       bool TAAParsed;
       std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
           Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
       if (!ErrorCode.empty()) {
-        report_fatal_error("Invalid section specifier '" + ParsedSection +
-                           "': " + ErrorCode + ".");
+        assert(false && "Invalid section specifier.");
+        return false;
       }
 
       // Ignore the globals from the __OBJC section. The ObjC runtime assumes
@@ -1196,18 +1208,6 @@
         return false;
       }
     }
-
-    // Callbacks put into the CRT initializer/terminator sections
-    // should not be instrumented.
-    // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
-    // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
-    if (Section.startswith(".CRT")) {
-      DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
-      return false;
-    }
-
-    // Globals from llvm.metadata aren't emitted, do not instrument them.
-    if (Section == "llvm.metadata") return false;
   }
 
   return true;
Index: test/Instrumentation/AddressSanitizer/do-not-instrument-llvm-metadata-darwin.ll
===================================================================
--- /dev/null
+++ test/Instrumentation/AddressSanitizer/do-not-instrument-llvm-metadata-darwin.ll
@@ -0,0 +1,12 @@
+; This test checks that we are not instrumenting globals in llvm.metadata.
+; RUN: opt < %s -asan -asan-module -S | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.10.0"
+
+ at .str_noinst = private unnamed_addr constant [4 x i8] c"aaa\00", section "llvm.metadata"
+ at .str_inst = private unnamed_addr constant [4 x i8] c"aaa\00"
+
+; CHECK-NOT: {{asan_gen.*str_noinst}}
+; CHECK: {{asan_gen.*str_inst}}
+; CHECK: @asan.module_ctor

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