[scudo] Fix secondary caching for mte

The current code always unmaps a secondary allocation when MTE is
enabled. Fix this to match the comment, namely only unmap if
MTE was enabled and is no longer enabled after acquiring the lock.

In addition, allow quaratine to work in the secondary even if MTE
is not enabled.

Author: cferris1000

compiler-rt/lib/scudo/standalone/secondary.h

@@ -269,7 +269,8 @@ class MapAllocatorCache {
     Entry.MemMap = MemMap;
     Entry.Time = UINT64_MAX;
 
-    if (useMemoryTagging<Config>(Options)) {
+    bool MemoryTaggingEnabled = useMemoryTagging<Config>(Options);
+    if (MemoryTaggingEnabled) {
       if (Interval == 0 && !SCUDO_FUCHSIA) {
         // Release the memory and make it inaccessible at the same time by
         // creating a new MAP_NOACCESS mapping on top of the existing mapping.
@@ -302,15 +303,16 @@ class MapAllocatorCache {
       if (Entry.Time != 0)
         Entry.Time = Time;
 
-      if (useMemoryTagging<Config>(Options) && QuarantinePos == -1U) {
+      if (MemoryTaggingEnabled && !useMemoryTagging<Config>(Options)) {
         // If we get here then memory tagging was disabled in between when we
         // read Options and when we locked Mutex. We can't insert our entry into
         // the quarantine or the cache because the permissions would be wrong so
         // just unmap it.
         unmapCallBack(Entry.MemMap);
         break;
       }
-      if (Config::getQuarantineSize() && useMemoryTagging<Config>(Options)) {
+
+      if (Config::getQuarantineSize()) {
         QuarantinePos =
             (QuarantinePos + 1) % Max(Config::getQuarantineSize(), 1u);
         if (!Quarantine[QuarantinePos].isValid()) {
@@ -513,9 +515,10 @@ class MapAllocatorCache {
         Quarantine[I].invalidate();
       }
     }
+    QuarantinePos = -1U;
+
     for (CachedBlock &Entry : LRUEntries)
       Entry.MemMap.setMemoryPermission(Entry.CommitBase, Entry.CommitSize, 0);
-    QuarantinePos = -1U;
   }
 
   void disable() NO_THREAD_SAFETY_ANALYSIS { Mutex.lock(); }