Index: lib/asan/asan_errors.h
===================================================================
--- lib/asan/asan_errors.h
+++ lib/asan/asan_errors.h
@@ -123,11 +123,30 @@
   void Print();
 };
 
-#define FOR_EACH_ERROR_KIND_MEMBER_NAME_PAIR(macro) \
-  macro(StackOverflow, stack_overflow)              \
-  macro(DeadlySignal, deadly_signal)                \
-  macro(DoubleFree, double_free)                    \
-  macro(NewDeleteSizeMismatch, new_delete_size_mismatch)
+struct ErrorFreeNotMalloced : ErrorBase {
+  u32 tid;
+  AddressDescriptionBase addr_description;
+  // ErrorFreeNotMalloced doesn't own the stack trace.
+  BufferedStackTrace *free_stack;
+  // VS2013 doesn't implement unrestricted unions, so we need a trivial default
+  // constructor
+  ErrorFreeNotMalloced() = default;
+  ErrorFreeNotMalloced(uptr addr, u32 tid_, BufferedStackTrace *stack)
+      : tid(tid_), free_stack(stack) {
+    addr_description =
+        AddressDescription(addr, /*shouldLockThreadRegistry=*/false);
+    scariness.Clear();
+    scariness.Scare(40, "bad-free");
+  }
+  void Print();
+};
+
+#define FOR_EACH_ERROR_KIND_MEMBER_NAME_PAIR(macro)      \
+  macro(StackOverflow, stack_overflow)                   \
+  macro(DeadlySignal, deadly_signal)                     \
+  macro(DoubleFree, double_free)                         \
+  macro(NewDeleteSizeMismatch, new_delete_size_mismatch) \
+  macro(FreeNotMalloced, free_not_malloced)
 
 enum ErrorKind {
   kErrorKindInvalid = 0,
Index: lib/asan/asan_errors.cc
===================================================================
--- lib/asan/asan_errors.cc
+++ lib/asan/asan_errors.cc
@@ -123,4 +123,22 @@
       "ASAN_OPTIONS=new_delete_type_mismatch=0\n");
 }
 
+void ErrorFreeNotMalloced::Print() {
+  Decorator d;
+  Printf("%s", d.Warning());
+  char tname[128];
+  Report(
+      "ERROR: AddressSanitizer: attempting free on address "
+      "which was not malloc()-ed: %p in thread T%d%s\n",
+      addr_description.Address(), tid,
+      ThreadNameWithParenthesis(tid, tname, sizeof(tname)));
+  Printf("%s", d.EndWarning());
+  CHECK_GT(free_stack->size, 0);
+  scariness.Print();
+  GET_STACK_TRACE_FATAL(free_stack->trace[0], free_stack->top_frame_bp);
+  stack.Print();
+  addr_description.Print();
+  ReportErrorSummary("bad-free", &stack);
+}
+
 }  // namespace __asan
Index: lib/asan/asan_report.cc
===================================================================
--- lib/asan/asan_report.cc
+++ lib/asan/asan_report.cc
@@ -350,20 +350,8 @@
 
 void ReportFreeNotMalloced(uptr addr, BufferedStackTrace *free_stack) {
   ScopedInErrorReport in_report;
-  Decorator d;
-  Printf("%s", d.Warning());
-  char tname[128];
-  u32 curr_tid = GetCurrentTidOrInvalid();
-  Report("ERROR: AddressSanitizer: attempting free on address "
-             "which was not malloc()-ed: %p in thread T%d%s\n", addr,
-         curr_tid, ThreadNameWithParenthesis(curr_tid, tname, sizeof(tname)));
-  Printf("%s", d.EndWarning());
-  CHECK_GT(free_stack->size, 0);
-  ScarinessScore::PrintSimple(40, "bad-free");
-  GET_STACK_TRACE_FATAL(free_stack->trace[0], free_stack->top_frame_bp);
-  stack.Print();
-  DescribeAddressIfHeap(addr);
-  ReportErrorSummary("bad-free", &stack);
+  ErrorFreeNotMalloced error(addr, GetCurrentTidOrInvalid(), free_stack);
+  in_report.ReportError(error);
 }
 
 void ReportAllocTypeMismatch(uptr addr, BufferedStackTrace *free_stack,