Chrome Version       : 71.0.3543.0 (Developer Build) (64-bit)
OS Version: OS X 10.13.6

What steps will reproduce the problem?
1. Start chrome with DCHECKs on, caBLE support and --enable-features="WebAuthenticationBle"
2. Trigger caBLE flow, e.g. by visiting accounts.google.com and logging into whitelisted account
3. Accept caBLE prompt on Phone

What is the expected result?
Sign-in succeeds and a redirect to myaccount.google.com happens.

What happens instead of that?
Chrome hits a DCHECK in FidoRequestHandlerBase::DeviceAdded [1].

Likely explanation:
During the caBLE flow multiple DeviceChanged notifications are sent. Once the caBLE device exposes the Fido service, the regular FidoBleDiscovery finds the device following one of the DeviceChanged notifications [2]. This will call DeviceAdded() and attempt to start a regular Fido BLE Handshake with the device. At some later point in time, the caBLE handshake completes and is validated, at which point DeviceAdded() is invoked another time [3]. This eventually will invoke FidoRequestHandlerBase::DeviceAdded a second time, hitting the DCHECK.

Possible Fix:
Stop the FidoBleDiscovery from connecting to the caBLE device. This could be achieved by replacing the GetDevice() call in FidoBleDiscovery::DeviceChanged with a similar one that checks FidoRequestHandlerBase' active_authenticators() instead.


Assigning to Jun, who is most familiar with this part of the code base.

Verbose Log Output and the first lines of Stack Trace following the crash follow:
[12082:775:0904/161524.962269:VERBOSE2:fido_ble_discovery_base.cc(63)] Got adapter AC:29:3A:F3:C9:01
[12082:775:0904/161524.962343:VERBOSE2:fido_ble_discovery.cc(34)] Adapter AC:29:3A:F3:C9:01 is powered on.
[12082:775:0904/161524.962559:VERBOSE2:fido_ble_discovery_base.cc(63)] Got adapter AC:29:3A:F3:C9:01
[12082:775:0904/161524.963629:VERBOSE2:fido_ble_discovery_base.cc(33)] Discovery session started.
[12082:775:0904/161524.967240:VERBOSE2:fido_cable_discovery.cc(234)] Discovery session started.
[12082:775:0904/161524.968513:ERROR:fido_cable_discovery.cc(277)] Failed to register advertisement: 1
[12082:775:0904/161524.985653:VERBOSE2:fido_cable_discovery.cc(270)] Advertisement registered.
[12082:775:0904/161533.369764:VERBOSE2:fido_cable_discovery.cc(173)] Discovered Cable device: E7:CF:87:DB:D7:D5
[12082:775:0904/161533.369828:VERBOSE2:fido_cable_discovery.cc(300)] Found new Cable device.
[12082:775:0904/161533.503552:VERBOSE2:fido_cable_discovery.cc(182)] Device changed for Cable device: E7:CF:87:DB:D7:D5
[12082:775:0904/161533.503617:VERBOSE2:fido_cable_discovery.cc(300)] Found new Cable device.
[12082:775:0904/161533.638454:VERBOSE2:fido_cable_discovery.cc(182)] Device changed for Cable device: E7:CF:87:DB:D7:D5
[12082:775:0904/161533.638525:VERBOSE2:fido_cable_discovery.cc(300)] Found new Cable device.
[12082:775:0904/161533.898063:VERBOSE2:fido_ble_connection.cc(296)] Got U2F Service: 0000fffd-0000-1000-8000-00805f9b34fb-0x7fa0fcc98280
[12082:775:0904/161533.898109:VERBOSE2:fido_ble_connection.cc(307)] Got U2F Control Point: f1d0fff1-deaa-ecee-b42f-c9ba7ed623bb-0x7fa107e363f0
[12082:775:0904/161533.898130:VERBOSE2:fido_ble_connection.cc(310)] Got U2F Status: f1d0fff2-deaa-ecee-b42f-c9ba7ed623bb-0x7fa107eb3260
[12082:775:0904/161533.898148:VERBOSE2:fido_ble_connection.cc(304)] Got U2F Control Point Length: f1d0fff3-deaa-ecee-b42f-c9ba7ed623bb-0x7fa107e981d0
[12082:775:0904/161533.898166:VERBOSE2:fido_ble_connection.cc(316)] Got U2F Service Revision Bitfield: f1d0fff4-deaa-ecee-b42f-c9ba7ed623bb-0x7fa107e642d0
[12082:775:0904/161533.898288:VERBOSE2:fido_ble_discovery.cc(70)] Discovered U2F service on existing BLE device: E7:CF:87:DB:D7:D5
[12082:775:0904/161533.898472:VERBOSE2:fido_ble_connection.cc(296)] Got U2F Service: 0000fffd-0000-1000-8000-00805f9b34fb-0x7fa0fcc98280
[12082:775:0904/161533.898506:VERBOSE2:fido_ble_connection.cc(307)] Got U2F Control Point: f1d0fff1-deaa-ecee-b42f-c9ba7ed623bb-0x7fa107e363f0
[12082:775:0904/161533.898528:VERBOSE2:fido_ble_connection.cc(310)] Got U2F Status: f1d0fff2-deaa-ecee-b42f-c9ba7ed623bb-0x7fa107eb3260
[12082:775:0904/161533.898548:VERBOSE2:fido_ble_connection.cc(304)] Got U2F Control Point Length: f1d0fff3-deaa-ecee-b42f-c9ba7ed623bb-0x7fa107e981d0
[12082:775:0904/161533.898569:VERBOSE2:fido_ble_connection.cc(316)] Got U2F Service Revision Bitfield: f1d0fff4-deaa-ecee-b42f-c9ba7ed623bb-0x7fa107e642d0
[12082:775:0904/161533.898640:VERBOSE2:fido_ble_connection.cc(132)] Error while reading Service Revision Bitfield: GATT_ERROR_IN_PROGRESS
[12082:775:0904/161533.898693:VERBOSE2:fido_ble_connection.cc(349)] Error: Could not obtain Service Revisions.
[12082:775:0904/161533.928000:VERBOSE2:fido_ble_connection.cc(123)] Detected Support for FIDO2.
[12082:775:0904/161533.958337:VERBOSE2:fido_ble_connection.cc(80)] Writing Remote Characteristic Succeeded.
[12082:775:0904/161533.987969:VERBOSE2:fido_ble_connection.cc(408)] Created notification session. Connection established.
[12082:775:0904/161534.017868:VERBOSE2:fido_ble_connection.cc(507)] Control Point Length: 101
[12082:775:0904/161534.047794:VERBOSE2:fido_ble_connection.cc(80)] Writing Remote Characteristic Succeeded.
[12082:775:0904/161534.063590:VERBOSE2:fido_ble_connection.cc(485)] Status characteristic value changed.
[12082:775:0904/161534.063702:VERBOSE2:fido_cable_discovery.cc(345)] Authenticator handshake validated
[12082:775:0904/161534.063735:FATAL:fido_request_handler_base.cc(188)] Check failed: !base::ContainsKey(active_authenticators(), device->GetId()).
0   libbase.dylib                       0x000000010dff5bbc base::debug::StackTrace::StackTrace(unsigned long) + 28
1   libbase.dylib                       0x000000010def36df logging::LogMessage::~LogMessage() + 223
2   libfido.dylib                       0x000000011910adab device::FidoRequestHandlerBase::DeviceAdded(device::FidoDiscovery*, device::FidoDevice*) + 123
3   libfido.dylib                       0x00000001191081f3 device::FidoDiscovery::AddDevice(std::__1::unique_ptr<device::FidoDevice, std::__1::default_delete<device::FidoDevice> >) + 339
4   libfido.dylib                       0x00000001190f97f6 device::FidoCableDiscovery::ValidateAuthenticatorHandshakeMessage(std::__1::unique_ptr<device::FidoCableDevice, std::__1::default_delete<device::FidoCableDevice> >, device::FidoCableHandshakeHandler*, base::Optional<std::__1::vector<unsigned char, std::__1::allocator<unsigned char> > >) + 198
...

[1] https://codesearch.chromium.org/chromium/src/device/fido/fido_request_handler_base.cc?l=188&rcl=ad2c0dc8c2bca1b767007ac3cacdb8652b566907
[2] https://codesearch.chromium.org/chromium/src/device/fido/ble/fido_ble_discovery.cc?l=72&rcl=9d1de57833ed7638965ccdc5ca184970858e44ec
[3] https://codesearch.chromium.org/chromium/src/device/fido/cable/fido_cable_discovery.cc?l=346&rcl=e34c38a4fc939f12788c1980c7db47929e24b96a