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Commit ab4d9f87 authored by Kevin Rocard's avatar Kevin Rocard
Browse files

IAudioPolicyService: Add attribute tags sanitization 



When audio_attributes_t was read from the binder parcel,
the string tags field was copied without checking that
it contained a '\0'.

This could lead to read past the end when tags were used.

This patch always adds a '\0' at the end of the buffer when
deserializing.

Bug: 68953950
Test: manual playback/record
Test: send binder payload without \0 in tags attribute, check that only
      AUDIO_ATTRIBUTES_TAGS_MAX_SIZE - 1 char are printed.
Change-Id: I285258cbf7cfaf26b191d1f31b3b1e2d724c4934
Merged-In: I285258cbf7cfaf26b191d1f31b3b1e2d724c4934
Signed-off-by: default avatarKevin Rocard <krocard@google.com>
parent 9dcb2547

include/media/IAudioPolicyService.h

+2 −0
Original line number Diff line number Diff line
@@ -177,6 +177,8 @@ public: 
                                    const Parcel& data,

                                    Parcel* reply,

                                    uint32_t flags = 0);

private:

    void sanetizeAudioAttributes(audio_attributes_t* attr);

};



// ----------------------------------------------------------------------------

media/libmedia/IAudioPolicyService.cpp

+12 −0
Original line number Diff line number Diff line
@@ -858,6 +858,7 @@ status_t BnAudioPolicyService::onTransact( 
            bool hasAttributes = data.readInt32() != 0;

            if (hasAttributes) {

                data.read(&attr, sizeof(audio_attributes_t));

                sanetizeAudioAttributes(&attr);

            }

            audio_session_t session = (audio_session_t)data.readInt32();

            audio_stream_type_t stream = AUDIO_STREAM_DEFAULT;
@@ -925,6 +926,7 @@ status_t BnAudioPolicyService::onTransact( 
            CHECK_INTERFACE(IAudioPolicyService, data, reply);

            audio_attributes_t attr;

            data.read(&attr, sizeof(audio_attributes_t));

            sanetizeAudioAttributes(&attr);

            audio_session_t session = (audio_session_t)data.readInt32();

            uid_t uid = (uid_t)data.readInt32();

            uint32_t samplingRate = data.readInt32();
@@ -1296,6 +1298,7 @@ status_t BnAudioPolicyService::onTransact( 
            data.read(&source, sizeof(struct audio_port_config));

            audio_attributes_t attributes;

            data.read(&attributes, sizeof(audio_attributes_t));

            sanetizeAudioAttributes(&attributes);

            audio_io_handle_t handle = {};

            status_t status = startAudioSource(&source, &attributes, &handle);

            reply->writeInt32(status);
@@ -1316,6 +1319,15 @@ status_t BnAudioPolicyService::onTransact( 
    }

}



void BnAudioPolicyService::sanetizeAudioAttributes(audio_attributes_t* attr)

{

    const size_t tagsMaxSize = AUDIO_ATTRIBUTES_TAGS_MAX_SIZE;

    if (strnlen(attr->tags, tagsMaxSize) >= tagsMaxSize) {

        android_errorWriteLog(0x534e4554, "68953950"); // SafetyNet logging

    }

    attr->tags[tagsMaxSize - 1] = '\0';

}



// ----------------------------------------------------------------------------



} // namespace android