Fix possible uaf of play policy state

Access to the play policy state may happen after
the state is freed in a race condition, which will
result in a SIGARBT.

SafetyNet logging is not added to avoid log spamming.
queryKeyStatus can be called often.

The crash was reproduced on the device before the fix.
Verified the test passes after the fix.

Test: sts-tradefed
  sts-tradefed run sts-engbuild-no-spl-lock -m StsHostTestCases --test android.security.sts.Bug_176486806#testPocBug_176486806

Test: push to device with target_hwasan-userdebug build
  adb shell /data/local/tmp/Bug-17648680664

Test: sts-tradefed
  sts-tradefed run sts-engbuild-no-spl-lock -m StsHostTestCases --test android.security.sts.Bug_176444154#testPocBug_176444154

Test: push to device with target_hwasan-userdebug build
  adb shell /data/local/tmp/Bug-17644415464

Bug: 176444154
Bug: 176486806
Change-Id: I07cc93c255942d56e866d0b08fb786f154f6e0d3
Merged-In: I07cc93c255942d56e866d0b08fb786f154f6e0d3

3 files changed, 4 insertions, 2 deletions

diff --git a/drm/mediadrm/plugins/clearkey/default/DrmPlugin.cpp b/drm/mediadrm/plugins/clearkey/default/DrmPlugin.cpp
index 6ac3510c7c..089eb1cdc9 100644
--- a/drm/mediadrm/plugins/clearkey/default/DrmPlugin.cpp
+++ b/drm/mediadrm/plugins/clearkey/default/DrmPlugin.cpp
@@ -207,6 +207,7 @@ status_t DrmPlugin::queryKeyStatus(
     }
 
     infoMap.clear();
+    android::Mutex::Autolock lock(mPlayPolicyLock);
     for (size_t i = 0; i < mPlayPolicy.size(); ++i) {
         infoMap.add(mPlayPolicy.keyAt(i), mPlayPolicy.valueAt(i));
     }
diff --git a/drm/mediadrm/plugins/clearkey/default/include/DrmPlugin.h b/drm/mediadrm/plugins/clearkey/default/include/DrmPlugin.h
index aa9b59ddbb..95f15caffe 100644
--- a/drm/mediadrm/plugins/clearkey/default/include/DrmPlugin.h
+++ b/drm/mediadrm/plugins/clearkey/default/include/DrmPlugin.h
@@ -262,7 +262,7 @@ private:
     void initProperties();
     void setPlayPolicy();
 
-    android::Mutex mPlayPolicyLock;
+    mutable android::Mutex mPlayPolicyLock;
     android::KeyedVector<String8, String8> mPlayPolicy;
     android::KeyedVector<String8, String8> mStringProperties;
     android::KeyedVector<String8, Vector<uint8_t>> mByteArrayProperties;
diff --git a/drm/mediadrm/plugins/clearkey/hidl/DrmPlugin.cpp b/drm/mediadrm/plugins/clearkey/hidl/DrmPlugin.cpp
index 15ebf78621..1ae4078288 100644
--- a/drm/mediadrm/plugins/clearkey/hidl/DrmPlugin.cpp
+++ b/drm/mediadrm/plugins/clearkey/hidl/DrmPlugin.cpp
@@ -563,7 +563,6 @@ Return<Status> DrmPlugin::setPropertyByteArray(
 Return<void> DrmPlugin::queryKeyStatus(
         const hidl_vec<uint8_t>& sessionId,
         queryKeyStatus_cb _hidl_cb) {
-
     if (sessionId.size() == 0) {
         // Returns empty key status KeyValue pair
         _hidl_cb(Status::BAD_VALUE, hidl_vec<KeyValue>());
@@ -573,12 +572,14 @@ Return<void> DrmPlugin::queryKeyStatus(
     std::vector<KeyValue> infoMapVec;
     infoMapVec.clear();
 
+    mPlayPolicyLock.lock();
     KeyValue keyValuePair;
     for (size_t i = 0; i < mPlayPolicy.size(); ++i) {
         keyValuePair.key = mPlayPolicy[i].key;
         keyValuePair.value = mPlayPolicy[i].value;
         infoMapVec.push_back(keyValuePair);
     }
+    mPlayPolicyLock.unlock();
     _hidl_cb(Status::OK, toHidlVec(infoMapVec));
     return Void();
 }