Catch some "easy to spot" double frees in TCMalloc

third_party/tcmalloc/chromium/src/free_list.cc

Index: third_party/tcmalloc/chromium/src/free_list.cc
===================================================================
--- third_party/tcmalloc/chromium/src/free_list.cc	(revision 101306)
+++ third_party/tcmalloc/chromium/src/free_list.cc	(working copy)
@@ -64,10 +64,18 @@
 #include <stddef.h>
 #include "internal_logging.h" //for ASSERT
 
+// TODO(jar): We should use C++ rather than a macro here.
 #define MEMORY_CHECK(v1, v2) \
   if (v1 != v2) CRASH("Memory corruption detected.\n")
 
 namespace {
+void EnusreNonLoop(void* node, void* next) {

[jschuh, 2011/09/28 23:13:11]

I think you meant EnsureNonLoop.

[jar (doing other things), 2011/09/29 22:30:57]

Done.

+  // We only have time to do minimal checking.  We don't traverse the list, but
+  // only look for an immediate loop (cycle back to ourself).
+  if (node != next) return;
+  CRASH("Circular loop in list detected: %p\n", next);
+}
+
 // Returns value of the |previous| pointer w/out running a sanity
 // check.
 inline void *FL_Previous_No_Check(void *t) {
@@ -88,10 +96,12 @@
 }
 
 inline void FL_SetPrevious(void *t, void *n) {
+  EnusreNonLoop(t, n);
   reinterpret_cast<void**>(t)[1] = n;
 }
 
 inline void FL_SetNext(void *t, void *n) {
+  EnusreNonLoop(t, n);
   reinterpret_cast<void**>(t)[0] = n;
 }