pyusb segfaults under macOS with devices stalling on a SET_INTERFACE request

https://github.com/libusb/libusb/issues/1011#issuecomment-983208629

For reference, we can reproduce this issue with a STM32F4-Discovery board, or SparkFun Thing Plus board (https://www.sparkfun.com/products/17712), using a libopencm3 example modified with this patch, which makes it stall the pipe on a SET_INTERFACE request. fw_set_interface_stall.patch.txt

Just a run log for reference using pyusb under my Mac Mini M1. Not so sure why pyusb segfaults though.

Tormod is suggesting that we look into the error processing path in pyusb.

mcuee@mcuees-Mac-mini ~ % export LIBUSB_DEBUG=4
mcuee@mcuees-Mac-mini ~ % python3
Python 3.9.8 (main, Nov 10 2021, 03:48:35)
[Clang 13.0.0 (clang-1300.0.29.3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import usb
>>> dev = usb.core.find(idVendor=0x0483)
[timestamp] [threadID] facility level [function call] <message>
--------------------------------------------------------------------------------
[ 0.000013] [00004d43] libusb: debug [libusb_init] libusb v1.0.24.11675
...

>>> dev.set_configuration()
[ 3.254908] [000075b5] libusb: debug [libusb_get_config_descriptor] index 0
[ 3.255204] [000075b5] libusb: debug [libusb_open] open 2.20
[ 3.255456] [000075b5] libusb: debug [darwin_open] device open for access
[ 3.255489] [000075b5] libusb: debug [libusb_set_configuration] configuration 1

>>> cfg = dev.get_active_configuration()
[15.680978] [000075b5] libusb: debug [libusb_get_config_descriptor] index 0
>>> print(cfg)
[21.631005] [000075b5] libusb: debug [libusb_get_config_descriptor] index 0
[21.631410] [000075b5] libusb: debug [libusb_get_config_descriptor] index 0
[21.631596] [000075b5] libusb: debug [libusb_get_config_descriptor] index 0
[21.631676] [000075b5] libusb: debug [libusb_get_config_descriptor] index 0
[21.631780] [000075b5] libusb: debug [libusb_get_config_descriptor] index 0
[21.631976] [000075b5] libusb: debug [libusb_get_config_descriptor] index 0
[21.632184] [000075b5] libusb: debug [libusb_get_config_descriptor] index 0
  CONFIGURATION 1: 100 mA ==================================
   bLength              :    0x9 (9 bytes)
   bDescriptorType      :    0x2 Configuration
   wTotalLength         :   0x43 (67 bytes)
   bNumInterfaces       :    0x2
   bConfigurationValue  :    0x1
   iConfiguration       :    0x0
   bmAttributes         :   0x80 Bus Powered
   bMaxPower            :   0x32 (100 mA)
    INTERFACE 0: Reserved ==================================
     bLength            :    0x9 (9 bytes)
     bDescriptorType    :    0x4 Interface
     bInterfaceNumber   :    0x0
     bAlternateSetting  :    0x0
     bNumEndpoints      :    0x1
     bInterfaceClass    :    0x0 Reserved
     bInterfaceSubClass :    0x2
     bInterfaceProtocol :    0x1
     iInterface         :    0x0
      ENDPOINT 0x83: Interrupt IN ==========================
       bLength          :    0x7 (7 bytes)
       bDescriptorType  :    0x5 Endpoint
       bEndpointAddress :   0x83 IN
       bmAttributes     :    0x3 Interrupt
       wMaxPacketSize   :   0x10 (16 bytes)
       bInterval        :   0xff
    INTERFACE 1: CDC Data ==================================
     bLength            :    0x9 (9 bytes)
     bDescriptorType    :    0x4 Interface
     bInterfaceNumber   :    0x1
     bAlternateSetting  :    0x0
     bNumEndpoints      :    0x2
     bInterfaceClass    :    0xa CDC Data
     bInterfaceSubClass :    0x0
     bInterfaceProtocol :    0x0
     iInterface         :    0x0
      ENDPOINT 0x1: Bulk OUT ===============================
       bLength          :    0x7 (7 bytes)
       bDescriptorType  :    0x5 Endpoint
       bEndpointAddress :    0x1 OUT
       bmAttributes     :    0x2 Bulk
       wMaxPacketSize   :   0x40 (64 bytes)
       bInterval        :    0x1
      ENDPOINT 0x82: Bulk IN ===============================
       bLength          :    0x7 (7 bytes)
       bDescriptorType  :    0x5 Endpoint
       bEndpointAddress :   0x82 IN
       bmAttributes     :    0x2 Bulk
       wMaxPacketSize   :   0x40 (64 bytes)
       bInterval        :    0x1

>>> dev.set_interface_altsetting(interface = 0, alternate_setting = 0)
[65.169062] [000075b5] libusb: debug [libusb_get_config_descriptor] index 0
[65.169440] [000075b5] libusb: debug [libusb_get_config_descriptor] index 0
[65.169628] [000075b5] libusb: debug [libusb_claim_interface] interface 0
[65.170967] [000075b5] libusb: debug [get_endpoints] building table of
endpoints.
[65.171743] [000075b5] libusb: debug [get_endpoints] interface: 0 pipe
1: dir: 1 number: 3
[65.171813] [000075b5] libusb: debug [darwin_claim_interface] interface opened
[65.171847] [000075b5] libusb: debug
[libusb_set_interface_alt_setting] interface 0 altsetting 0
[65.176102] [000075b5] libusb: warning
[darwin_set_interface_altsetting] SetAlternateInterface: pipe is
stalled
[65.176876] [000075b5] libusb: info [darwin_claim_interface]
USBInterfaceOpen: another process has device opened for exclusive
access
[65.177150] [000075b5] libusb: error [darwin_set_interface_altsetting]
could not reclaim interface
zsh: segmentation fault  python3

[mcuee]

We can always reopen if later we think there are changes required for pyusb.

[mcuee]

Can you get a log with PYUSB_DEBUG=debug set?

Yes I will post a log this evening.

Also, what version of PyUSB is being used?

Git head version of pyusb.