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Commit e637aa32 authored by Nick Desaulniers's avatar Nick Desaulniers
Browse files

biometrics: fingerprint: add locking to default impl 

There exists the following race condition:
a). thread A receives setNotify and sets the callback to some object
b). thread B of the wrapped implementation calls
BiometricsFingerprint::notify which it was given a handle to. Thread B
executes past the nullptr check:
c). thread A receives setNotify and sets the callback to some other
object (or nullptr)
d). thread B resumes in notify with unknown state

Add mutex to protect access to mClientCallback.

Change-Id: I9163204ff5802e9246056caeb2a7857e6138531c
Fixes: 64802340
Test: VtsHalBiometricsFingerprintV2_1IfaceFuzzer
parent b96a339f

biometrics/fingerprint/2.1/default/BiometricsFingerprint.cpp

+2 −0
Original line number Diff line number Diff line
@@ -145,6 +145,7 @@ FingerprintAcquiredInfo BiometricsFingerprint::VendorAcquiredFilter( 


Return<uint64_t> BiometricsFingerprint::setNotify(

        const sp<IBiometricsFingerprintClientCallback>& clientCallback) {

    std::lock_guard<std::mutex> lock(mClientCallbackMutex);

    mClientCallback = clientCallback;

    // This is here because HAL 2.1 doesn't have a way to propagate a

    // unique token for its driver. Subsequent versions should send a unique
@@ -259,6 +260,7 @@ fingerprint_device_t* BiometricsFingerprint::openHal() { 
void BiometricsFingerprint::notify(const fingerprint_msg_t *msg) {

    BiometricsFingerprint* thisPtr = static_cast<BiometricsFingerprint*>(

            BiometricsFingerprint::getInstance());

    std::lock_guard<std::mutex> lock(thisPtr->mClientCallbackMutex);

    if (thisPtr == nullptr || thisPtr->mClientCallback == nullptr) {

        ALOGE("Receiving callbacks before the client callback is registered.");

        return;

biometrics/fingerprint/2.1/default/BiometricsFingerprint.h

+1 −0
Original line number Diff line number Diff line
@@ -69,6 +69,7 @@ private: 
    static FingerprintAcquiredInfo VendorAcquiredFilter(int32_t error, int32_t* vendorCode);

    static BiometricsFingerprint* sInstance;



    std::mutex mClientCallbackMutex;

    sp<IBiometricsFingerprintClientCallback> mClientCallback;

    fingerprint_device_t *mDevice;

};