Aleksander Morgado
822bfa4ca1
Since commit e9d0989ed0, the MMDevice may be removed from the
tracking hash table when the support check operation fails to create a
modem object.
If this failure happens due to the port probe cancellations requested
during the udev removal event for a given device port, we would end up
using an already disposed object and triggering a segfault.
This fix just makes sure a full valid reference to the MMDevice object
is kept around until we're done using it.
[mm-base-manager.c:216] device_removed(): (usbmisc/cdc-wdm1): released by device '/sys/devices/pci0000:00/0000:00:1d.0/usb1/1-1/1-1.4'
[mm-plugin-manager.c:1131] device_context_port_released(): [plugin manager] task 5: port released: cdc-wdm1
[mm-base-manager.c:216] device_removed(): (tty/ttyACM0): released by device '/sys/devices/pci0000:00/0000:00:1d.0/usb1/1-1/1-1.4'
[mm-plugin-manager.c:1131] device_context_port_released(): [plugin manager] task 5: port released: ttyACM0
[mm-base-manager.c:221] device_removed(): Removing empty device '/sys/devices/pci0000:00/0000:00:1d.0/usb1/1-1/1-1.4'
[mm-plugin-manager.c:1219] device_context_cancel(): [plugin manager) task 5: cancellation requested
[mm-plugin-manager.c:979] device_context_continue(): [plugin manager] task 5: no more ports to probe
[mm-plugin-manager.c:813] device_context_complete(): [plugin manager] task 5: finished in '0.090510' seconds
[mm-base-manager.c:172] device_support_check_ready(): Couldn't check support for device '/sys/devices/pci0000:00/0000:00:1d.0/usb1/1-1/1-1.4': Operation was cancelled
[mm-base-manager.c:223] device_removed(): Device support check has been cancelled
Thread 1 "ModemManager" received signal SIGSEGV, Segmentation fault.
0x00007ffff6543c50 in g_str_hash () from /usr/lib/libglib-2.0.so.0
(gdb) bt
#0 0x00007ffff6543c50 in g_str_hash () at /usr/lib/libglib-2.0.so.0
#1 0x00007ffff6542b2d in () at /usr/lib/libglib-2.0.so.0
#2 0x0000000000439675 in device_removed (self=0x770900, kernel_device=0x763e60) at mm-base-manager.c:225
#3 0x0000000000439e70 in handle_uevent (client=0x769c20, action=0x81d910 "remove", device=0x7fffe4001c40, user_data=0x770900) at mm-base-manager.c:415
#4 0x00007ffff54c61c8 in ffi_call_unix64 () at /usr/lib/libffi.so.6
#5 0x00007ffff54c5c2a in ffi_call () at /usr/lib/libffi.so.6
#6 0x00007ffff682d7ae in g_cclosure_marshal_generic ()
at /usr/lib/libgobject-2.0.so.0
#7 0x00007ffff682cf75 in g_closure_invoke () at /usr/lib/libgobject-2.0.so.0
#8 0x00007ffff683ef82 in () at /usr/lib/libgobject-2.0.so.0
#9 0x00007ffff6847bcc in g_signal_emit_valist ()
at /usr/lib/libgobject-2.0.so.0
#10 0x00007ffff6847faf in g_signal_emit () at /usr/lib/libgobject-2.0.so.0
#11 0x00007ffff7023c74 in () at /usr/lib/libgudev-1.0.so.0
#12 0x00007ffff655445a in g_main_context_dispatch ()
at /usr/lib/libglib-2.0.so.0
#13 0x00007ffff6554810 in () at /usr/lib/libglib-2.0.so.0
#14 0x00007ffff6554b32 in g_main_loop_run () at /usr/lib/libglib-2.0.so.0
#15 0x0000000000437bf5 in main (argc=2, argv=0x7fffffffeb28) at
main.c:180
(gdb) fr 2
#2 0x0000000000439675 in device_removed (self=0x770900, kernel_device=0x763e60) at mm-base-manager.c:225
225 g_hash_table_remove (self->priv->devices, mm_device_get_uid (device));
(gdb) p mm_device_get_uid (device)
$1 = (const gchar *) 0x0
(gdb) p *device
$3 = {parent = {g_type_instance = {g_class = 0x0}, ref_count = 0, qdata = 0x0}, priv = 0x7feb20}
ModemManager. ModemManager provides a unified high level API for communicating with mobile broadband modems, regardless of the protocol used to communicate with the actual device (Generic AT, vendor-specific AT, QCDM, QMI, MBIM...). Using. ModemManager is a system daemon and is not meant to be used directly from the command line. However, since it provides a DBus API, it is possible to use 'dbus-send' commands or the new 'mmcli' command line interface to control it from the terminal. The devices are queried from udev and automatically updated based on hardware events, although a manual re-scan can also be requested to look for RS232 modems. Implementation. ModemManager is a DBus system bus activated service (meaning it's started automatically when a request arrives). It is written in C, using glib and gio. Several GInterfaces specify different features that the modems support, including the generic MMIfaceModem3gpp and MMIfaceModemCdma which provice basic operations for 3GPP (GSM, UMTS, LTE) or CDMA (CDMA1x, EV-DO) modems. If a given feature is not available in the modem, the specific interface will not be exported in DBus. Plugins. Plugins are loaded on startup, and must implement the MMPlugin interface. It consists of a couple of methods which tell the daemon whether the plugin supports a port and to create custom MMBroadbandModem implementations. It most likely makes sense to derive custom modem implementations from one of the generic classes and just add (or override) operations which are not standard. There are multiple fully working plugins in the plugins/ directory that can be used as an example for writing new plugins. Writing new plugins is highly encouraged! The plugin API is open for changes, so if you're writing a plugin and need to add or change some public method, feel free to suggest it! License. The ModemManager and mmcli binaries are both GPLv2+. The libmm-glib library is LGPLv2+.