From ba3e8933c88d5f02de85fba1e194a4a072321ed4 Mon Sep 17 00:00:00 2001
From: Rahul Frias <rfrias@google.com>
Date: Wed, 25 Jul 2018 22:59:11 -0700
Subject: [PATCH] Avoid sending clear subsamples to the decoder before keys are
 loaded

[ Merge of http://go/wvgerrit/54880 ]

Sending clear subsamples but filtering out encrypted ones,
before the keys have been loaded, causes problems during decode.
This is because subsamples that contain the first and last
subsample flags may be filtered out.

Clear subsamples that have first and last subsample flags set
will still be allowed to be passed to the decoder.

Bug: 110251447
Bug: 73447733
Test: WV Unit/integration tests.
Change-Id: I8c91c88f6313ad7b7b21c1c95e4c5787381949c1
---
 .../cdm/src/wv_content_decryption_module.cpp  | 12 +++--
 .../cdm/test/request_license_test.cpp         | 46 +++++++++++++++++--
 2 files changed, 50 insertions(+), 8 deletions(-)

diff --git a/libwvdrmengine/cdm/src/wv_content_decryption_module.cpp b/libwvdrmengine/cdm/src/wv_content_decryption_module.cpp
index 1c5f5394..de6ed70b 100644
--- a/libwvdrmengine/cdm/src/wv_content_decryption_module.cpp
+++ b/libwvdrmengine/cdm/src/wv_content_decryption_module.cpp
@@ -327,10 +327,14 @@ CdmResponseType WvContentDecryptionModule::Decrypt(
         cdm_engine->FindSessionForKey(*parameters.key_id, &local_session_id);
     cdm_engine->GetMetrics()->cdm_engine_find_session_for_key_.Increment(
         status);
-    if (!status && parameters.is_encrypted) {
-      LOGE("WvContentDecryptionModule::Decrypt: unable to find session: %s",
-           session_id.c_str());
-      return KEY_NOT_FOUND_IN_SESSION;
+    if (!status) {
+      // key does not need to be loaded if clear lead/frame has a
+      // single subsample. It does in all other cases.
+      if (parameters.is_encrypted ||
+          !(parameters.subsample_flags & OEMCrypto_FirstSubsample) ||
+          !(parameters.subsample_flags & OEMCrypto_LastSubsample)) {
+        return KEY_NOT_FOUND_IN_SESSION;
+      }
     }
   }
   CdmResponseType sts;
diff --git a/libwvdrmengine/cdm/test/request_license_test.cpp b/libwvdrmengine/cdm/test/request_license_test.cpp
index 5b9c0f6b..570283b5 100644
--- a/libwvdrmengine/cdm/test/request_license_test.cpp
+++ b/libwvdrmengine/cdm/test/request_license_test.cpp
@@ -100,6 +100,39 @@ SubSampleInfo clear_sub_sample = {
     wvcdm::a2b_hex("f6f4b1e600a5b67813ed2bded913ba9f"), 0,
     OEMCrypto_FirstSubsample | OEMCrypto_LastSubsample};
 
+SubSampleInfo clear_sub_samples[2] = {
+  // block 0, key SD, encrypted, 128b
+  { true, 1, true, false, false,
+    wvcdm::a2bs_hex("371EA35E1A985D75D198A7F41020DC23"),
+    wvcdm::a2b_hex(
+        "217ce9bde99bd91e9733a1a00b9b557ac3a433dc92633546156817fae26b6e1c"
+        "942ac20a89ff79f4c2f25fba99d6a44618a8c0420b27d54e3da17b77c9d43cca"
+        "595d259a1e4a8b6d7744cd98c5d3f921adc252eb7d8af6b916044b676a574747"
+        "8df21fdc42f166880d97a2225cd5c9ea5e7b752f4cf81bbdbe98e542ee10e1c6"),
+    wvcdm::a2b_hex(
+        "217ce9bde99bd91e9733a1a00b9b557ac3a433dc92633546156817fae26b6e1c"
+        "942ac20a89ff79f4c2f25fba99d6a44618a8c0420b27d54e3da17b77c9d43cca"
+        "595d259a1e4a8b6d7744cd98c5d3f921adc252eb7d8af6b916044b676a574747"
+        "8df21fdc42f166880d97a2225cd5c9ea5e7b752f4cf81bbdbe98e542ee10e1c6"),
+    wvcdm::a2b_hex("f6f4b1e600a5b67813ed2bded913ba9f"), 0,
+    OEMCrypto_FirstSubsample},
+  // block 1, key SD, encrypted, 128b
+  { true, 1, true, false, false,
+    wvcdm::a2bs_hex("371EA35E1A985D75D198A7F41020DC23"),
+    wvcdm::a2b_hex(
+        "ad868a6ac55c10d564fc23b8acff407daaf4ed2743520e02cda9680d9ea88e91"
+        "029359c4cf5906b6ab5bf60fbb3f1a1c7c59acfc7e4fb4ad8e623c04d503a3dd"
+        "4884604c8da8a53ce33db9ff8f1c5bb6bb97f37b39906bf41596555c1bcce9ed"
+        "08a899cd760ff0899a1170c2f224b9c52997a0785b7fe170805fd3e8b1127659"),
+    wvcdm::a2b_hex(
+        "ad868a6ac55c10d564fc23b8acff407daaf4ed2743520e02cda9680d9ea88e91"
+        "029359c4cf5906b6ab5bf60fbb3f1a1c7c59acfc7e4fb4ad8e623c04d503a3dd"
+        "4884604c8da8a53ce33db9ff8f1c5bb6bb97f37b39906bf41596555c1bcce9ed"
+        "08a899cd760ff0899a1170c2f224b9c52997a0785b7fe170805fd3e8b1127659"),
+    wvcdm::a2b_hex("f6f4b1e600a5b67813ed2bded913ba9f"), 0,
+    OEMCrypto_LastSubsample}
+};
+
 SubSampleInfo clear_sub_sample_no_key = {
     false, 1, false, false, false,
     wvcdm::a2bs_hex("77777777777777777777777777777777"),
@@ -4695,10 +4728,13 @@ TEST_P(WvCdmSessionSharingNoKeyTest, DecryptionTest) {
   decryption_parameters.is_secure = data->is_secure;
   decryption_parameters.subsample_flags = data->subsample_flags;
 
-    EXPECT_EQ(data->is_encrypted ? KEY_NOT_FOUND_IN_SESSION : NO_ERROR,
-              decryptor_.Decrypt(gp_session_id_2, data->validate_key_id,
-                                 decryption_parameters));
-  if (!data->is_encrypted) {
+  bool can_decrypt = !data->is_encrypted &&
+      data->subsample_flags & OEMCrypto_FirstSubsample &&
+      data->subsample_flags & OEMCrypto_LastSubsample;
+  EXPECT_EQ(can_decrypt ? NO_ERROR : KEY_NOT_FOUND_IN_SESSION,
+            decryptor_.Decrypt(gp_session_id_2, data->validate_key_id,
+                               decryption_parameters));
+  if (can_decrypt) {
     EXPECT_TRUE(std::equal(data->decrypt_data.begin(), data->decrypt_data.end(),
                            decrypt_buffer.begin()));
   }
@@ -4709,6 +4745,8 @@ TEST_P(WvCdmSessionSharingNoKeyTest, DecryptionTest) {
 
 INSTANTIATE_TEST_CASE_P(Cdm, WvCdmSessionSharingNoKeyTest,
                         ::testing::Values(&clear_sub_sample,
+                                          &clear_sub_samples[0],
+                                          &clear_sub_samples[1],
                                           &clear_sub_sample_no_key,
                                           &single_encrypted_sub_sample));