Fixed race condition in closeSession

Merged from http://go/wvgerrit/165061
poc: http://go/ag/20978750

Fix race that corrupts mCryptoSessions std::map,
and race that occurs when CryptoSessions are used after free.

Test: poc
Test: atest MediaDrmParameterizedTests
Test: atest GtsMediaTestCases

Bug: 258189255
Change-Id: I298d3e0770ace9cd590dfaacaa4c52a0732c2fe3
Merged-In: I298d3e0770ace9cd590dfaacaa4c52a0732c2fe3

libwvdrmengine/mediadrm/aidl_include/WVDrmPlugin.h

@@ -14,6 +14,7 @@
 
 #include <list>
 #include <map>
+#include <mutex>
 
 #include "OEMCryptoCENC.h"
 #include "WVGenericCryptoInterface.h"
@@ -395,9 +396,46 @@ struct WVDrmPlugin : public ::aidl::android::hardware::drm::BnDrmPlugin,
     android::Mutex mLock;
   };
 
+  class CryptoSessionMap {
+   public:
+    std::map<CdmSessionId, std::shared_ptr<CryptoSession>> clear() {
+      std::unique_lock<std::mutex> auto_lock(mLock);
+      auto copy = mMap;
+      mMap.clear();
+      return copy;
+    }
+
+    std::shared_ptr<CryptoSession> get(const CdmSessionId& sid) {
+      std::unique_lock<std::mutex> auto_lock(mLock);
+      if (mMap.count(sid)) {
+        return mMap[sid];
+      }
+      return nullptr;
+    }
+
+    bool empty() {
+      std::unique_lock<std::mutex> auto_lock(mLock);
+      return mMap.empty();
+    }
+
+    void erase(const CdmSessionId& sid) {
+      std::unique_lock<std::mutex> auto_lock(mLock);
+      mMap.erase(sid);
+    }
+
+    void insert(const CdmSessionId& sid, OEMCrypto_SESSION osid) {
+      std::unique_lock<std::mutex> auto_lock(mLock);
+      mMap[sid] = std::make_shared<CryptoSession>(osid);
+    }
+
+   private:
+     std::mutex mLock;
+     std::map<CdmSessionId, std::shared_ptr<CryptoSession>> mMap;
+  };
+
   android::sp<wvcdm::WvContentDecryptionModule> const mCDM;
   WVGenericCryptoInterface* mCrypto;
-  std::map<CdmSessionId, CryptoSession> mCryptoSessions;
+  CryptoSessionMap mCryptoSessions;
   std::shared_ptr<::aidl::android::hardware::drm::IDrmPluginListener> mListener;
 
   std::string mProvisioningServiceCertificate;