Protect Session ID List With a Lock

(This is a merge of
https://widevine-internal-review.googlesource.com/#/c/11405
from the Widevine CDM Repo.)

AUPT is revealing a crash when destructing WVDrmPlugin due to
multi-threaded contention over the session map. As a fix, we are now
protecting access to the map via a mutex.

Bug: 17761616
Change-Id: Iddeca657effd3c7f3ff35ce334d7979291667cef

libwvdrmengine/mediadrm/include/WVDrmPlugin.h

@@ -16,6 +16,7 @@
 #include "utils/Errors.h"
 #include "utils/KeyedVector.h"
 #include "utils/List.h"
+#include "utils/Mutex.h"
 #include "utils/String8.h"
 #include "utils/Vector.h"
 #include "wv_cdm_event_listener.h"
@@ -26,6 +27,7 @@ namespace wvdrm {
 
 using android::KeyedVector;
 using android::List;
+using android::Mutex;
 using android::status_t;
 using android::String8;
 using android::Vector;
@@ -229,6 +231,7 @@ class WVDrmPlugin : public android::DrmPlugin,
 
   WvContentDecryptionModule* mCDM;
   WVGenericCryptoInterface* mCrypto;
+  Mutex mCryptoSessionsMutex;
   map<CdmSessionId, CryptoSession> mCryptoSessions;
 
   status_t mapAndNotifyOfCdmResponseType(const Vector<uint8_t>& sessionId,

libwvdrmengine/mediadrm/src/WVDrmPlugin.cpp

@@ -35,10 +35,11 @@ using namespace wvcdm;
 
 WVDrmPlugin::WVDrmPlugin(WvContentDecryptionModule* cdm,
                          WVGenericCryptoInterface* crypto)
-  : mCDM(cdm), mCrypto(crypto) {}
+  : mCDM(cdm), mCrypto(crypto), mCryptoSessionsMutex(), mCryptoSessions() {}
 
 WVDrmPlugin::~WVDrmPlugin() {
   typedef map<CdmSessionId, CryptoSession>::iterator mapIterator;
+  Mutex::Autolock lock(mCryptoSessionsMutex);
   for (mapIterator iter = mCryptoSessions.begin();
        iter != mCryptoSessions.end();
        ++iter) {
@@ -82,7 +83,10 @@ status_t WVDrmPlugin::openSession(Vector<uint8_t>& sessionId) {
       OEMCrypto_SESSION oecSessionId;
       istringstream(info[QUERY_KEY_OEMCRYPTO_SESSION_ID]) >> oecSessionId;
 
+      {
+        Mutex::Autolock lock(mCryptoSessionsMutex);
         mCryptoSessions[cdmSessionId] = CryptoSession(oecSessionId);
+      }
 
       success = true;
     } else {
@@ -123,6 +127,7 @@ status_t WVDrmPlugin::closeSession(const Vector<uint8_t>& sessionId) {
   CdmResponseType res = mCDM->CloseSession(cdmSessionId);
 
   if (isCdmResponseTypeSuccess(res)) {
+    Mutex::Autolock lock(mCryptoSessionsMutex);
     mCryptoSessions.erase(cdmSessionId);
   }
 
@@ -559,7 +564,12 @@ status_t WVDrmPlugin::getPropertyByteArray(const String8& name,
 status_t WVDrmPlugin::setPropertyString(const String8& name,
                                         const String8& value) {
   if (name == "securityLevel") {
-    if (mCryptoSessions.size() == 0) {
+    size_t sessionCount = 0;
+    {
+      Mutex::Autolock lock(mCryptoSessionsMutex);
+      sessionCount = mCryptoSessions.size();
+    }
+    if (sessionCount == 0) {
       if (value == QUERY_VALUE_SECURITY_LEVEL_L3.c_str()) {
         mPropertySet.set_security_level(QUERY_VALUE_SECURITY_LEVEL_L3);
       } else if (value == QUERY_VALUE_SECURITY_LEVEL_L1.c_str()) {
@@ -600,7 +610,12 @@ status_t WVDrmPlugin::setPropertyString(const String8& name,
       return android::BAD_VALUE;
     }
   } else if (name == "sessionSharing") {
-    if (mCryptoSessions.size() == 0) {
+    size_t sessionCount = 0;
+    {
+      Mutex::Autolock lock(mCryptoSessionsMutex);
+      sessionCount = mCryptoSessions.size();
+    }
+    if (sessionCount == 0) {
       if (value == kEnable) {
         mPropertySet.set_is_session_sharing_enabled(true);
       } else if (value == kDisable) {
@@ -637,6 +652,7 @@ status_t WVDrmPlugin::setPropertyByteArray(const String8& name,
 status_t WVDrmPlugin::setCipherAlgorithm(const Vector<uint8_t>& sessionId,
                                          const String8& algorithm) {
   CdmSessionId cdmSessionId(sessionId.begin(), sessionId.end());
+  Mutex::Autolock lock(mCryptoSessionsMutex);
 
   if (!mCryptoSessions.count(cdmSessionId)) {
     return android::ERROR_DRM_SESSION_NOT_OPENED;
@@ -656,6 +672,7 @@ status_t WVDrmPlugin::setCipherAlgorithm(const Vector<uint8_t>& sessionId,
 status_t WVDrmPlugin::setMacAlgorithm(const Vector<uint8_t>& sessionId,
                                       const String8& algorithm) {
   CdmSessionId cdmSessionId(sessionId.begin(), sessionId.end());
+  Mutex::Autolock lock(mCryptoSessionsMutex);
 
   if (!mCryptoSessions.count(cdmSessionId)) {
     return android::ERROR_DRM_SESSION_NOT_OPENED;
@@ -678,6 +695,7 @@ status_t WVDrmPlugin::encrypt(const Vector<uint8_t>& sessionId,
                               const Vector<uint8_t>& iv,
                               Vector<uint8_t>& output) {
   CdmSessionId cdmSessionId(sessionId.begin(), sessionId.end());
+  Mutex::Autolock lock(mCryptoSessionsMutex);
 
   if (!mCryptoSessions.count(cdmSessionId)) {
     return android::ERROR_DRM_SESSION_NOT_OPENED;
@@ -717,6 +735,7 @@ status_t WVDrmPlugin::decrypt(const Vector<uint8_t>& sessionId,
                               const Vector<uint8_t>& iv,
                               Vector<uint8_t>& output) {
   CdmSessionId cdmSessionId(sessionId.begin(), sessionId.end());
+  Mutex::Autolock lock(mCryptoSessionsMutex);
 
   if (!mCryptoSessions.count(cdmSessionId)) {
     return android::ERROR_DRM_SESSION_NOT_OPENED;
@@ -755,6 +774,7 @@ status_t WVDrmPlugin::sign(const Vector<uint8_t>& sessionId,
                            const Vector<uint8_t>& message,
                            Vector<uint8_t>& signature) {
   CdmSessionId cdmSessionId(sessionId.begin(), sessionId.end());
+  Mutex::Autolock lock(mCryptoSessionsMutex);
 
   if (!mCryptoSessions.count(cdmSessionId)) {
     return android::ERROR_DRM_SESSION_NOT_OPENED;
@@ -810,6 +830,7 @@ status_t WVDrmPlugin::verify(const Vector<uint8_t>& sessionId,
                              const Vector<uint8_t>& signature,
                              bool& match) {
   CdmSessionId cdmSessionId(sessionId.begin(), sessionId.end());
+  Mutex::Autolock lock(mCryptoSessionsMutex);
 
   if (!mCryptoSessions.count(cdmSessionId)) {
     return android::ERROR_DRM_SESSION_NOT_OPENED;