[WinASan] Don't instrument globals in sections containing '$'

Such globals are very likely to be part of a sorted section array, such
the .CRT sections used for dynamic initialization. The uses its own
sorted sections called ATL$__a, ATL$__m, and ATL$__z. Instead of special
casing them, just look for the dollar sign, which is what invokes linker
section sorting for COFF.

Avoids issues with ASan and the ATL uncovered after we started
instrumenting comdat globals on COFF.

llvm-svn: 334653

1 files changed, 9 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index d5903c74585..a9936018b43 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -1710,13 +1710,17 @@ bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
       return false;
     }
 
-    // Callbacks put into the CRT initializer/terminator sections
-    // should not be instrumented.
+    // On COFF, if the section name contains '$', it is highly likely that the
+    // user is using section sorting to create an array of globals similar to
+    // the way initialization callbacks are registered in .init_array and
+    // .CRT$XCU. The ATL also registers things in .ATL$__[azm]. Adding redzones
+    // to such globals is counterproductive, because the intent is that they
+    // will form an array, and out-of-bounds accesses are expected.
     // See https://github.com/google/sanitizers/issues/305
     // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
-    if (Section.startswith(".CRT")) {
-      LLVM_DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G
-                        << "\n");
+    if (TargetTriple.isOSBinFormatCOFF() && Section.contains('$')) {
+      LLVM_DEBUG(dbgs() << "Ignoring global in sorted section (contains '$'): "
+                        << *G << "\n");
       return false;
     }