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Address key selection and decryption concurrency issues

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Decryption calls though multiple threads may result in race conditions
between the setting of the key and the actual call to decryption.
This results in OEMCrypto errors when the buffer type used in
decryption did not match the key selected. This is addressed by
having the the two calls be in the same critical section.

b/11009857

Change-Id: I74f1a0689ca17114f3cdd029022013b05c415acd
This commit is contained in:
Rahul Frias
2013-10-02 15:43:28 -07:00
parent 67c794bac3
commit a74980b2f1
3 changed files with 14 additions and 12 deletions
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2
libwvdrmengine/cdm/core/include/crypto_session.h
View File

@@ -92,6 +92,8 @@ class CryptoSession {
bool is_destination_buffer_type_valid_;
SecurityLevel requested_security_level_;
KeyId key_id_;
CORE_DISALLOW_COPY_AND_ASSIGN(CryptoSession);
};

11
libwvdrmengine/cdm/core/src/cdm_session.cpp
View File

@@ -272,17 +272,6 @@ CdmResponseType CdmSession::Decrypt(const CdmDecryptionParameters& params) {
if (crypto_session_.get() == NULL || !crypto_session_->IsOpen())
return UNKNOWN_ERROR;
// Check if key needs to be selected
if (params.is_encrypted) {
if (key_id_.compare(*params.key_id) != 0) {
if (crypto_session_->SelectKey(*params.key_id)) {
key_id_ = *params.key_id;
} else {
return NEED_KEY;
}
}
}
return crypto_session_->Decrypt(params);
}

13
libwvdrmengine/cdm/core/src/crypto_session.cpp
View File

@@ -433,7 +433,6 @@ bool CryptoSession::RefreshKeys(const std::string& message,
}
bool CryptoSession::SelectKey(const std::string& key_id) {
AutoLock auto_lock(crypto_lock_);
const uint8_t* key_id_string =
reinterpret_cast<const uint8_t*>(key_id.data());
@@ -550,6 +549,18 @@ CdmResponseType CryptoSession::Decrypt(const CdmDecryptionParameters& params) {
if (!SetDestinationBufferType()) return UNKNOWN_ERROR;
}
AutoLock auto_lock(crypto_lock_);
// Check if key needs to be selected
if (params.is_encrypted) {
if (key_id_.compare(*params.key_id) != 0) {
if (SelectKey(*params.key_id)) {
key_id_ = *params.key_id;
} else {
return NEED_KEY;
}
}
}
OEMCrypto_DestBufferDesc buffer_descriptor;
buffer_descriptor.type =
params.is_secure ? destination_buffer_type_ : OEMCrypto_BufferType_Clear;