device: handle NULL returned by g_udev_device_get_driver() gracefully
This patch fixes a crash in mm_device_grab_port() when doing a string
comparison on a NULL returned by g_udev_device_get_driver().
Thread 0 *CRASHED* ( SIGSEGV @ 0x00000000 )
0x76b760b4 [libc-2.15.so] - strcmp.c:38 strcmp
0x76c66a7d [libglib-2.0.so.0.3200.4] - ghash.c:1704 g_str_equal
0x76ee0e5d [ModemManager] - mm-device.c:147 mm_device_grab_port
0x76edf9d9 [ModemManager] - mm-manager.c:313 device_added
0x76e95b2d [libgudev-1.0.so.0.1.0] - extras/gudev/gudevmarshal.c:84 g_udev_marshal_VOID__STRING_OBJECT
0x76d1fb2b [libgobject-2.0.so.0.3200.4] - gclosure.c:777 g_closure_invoke
0x76d2b88b [libgobject-2.0.so.0.3200.4] - gsignal.c:3551 signal_emit_unlocked_R
0x76d313c5 [libgobject-2.0.so.0.3200.4] - gsignal.c:3300 g_signal_emit_valist
0x76d31569 [libgobject-2.0.so.0.3200.4] - gsignal.c:3356 g_signal_emit
0x76e93bdd [libgudev-1.0.so.0.1.0] - extras/gudev/gudevclient.c:105 monitor_event
0x76c9beb7 [libglib-2.0.so.0.3200.4] - giounix.c:166 g_io_unix_dispatch
0x76c714c1 [libglib-2.0.so.0.3200.4] - gmain.c:2539 g_main_context_dispatch
0x76c71745 [libglib-2.0.so.0.3200.4] - gmain.c:3146 g_main_context_iterate
0x76c71a59 [libglib-2.0.so.0.3200.4] - gmain.c:3340 g_main_loop_run
0x76ede8ed [ModemManager] - main.c:142 main
0x76b35f79 [libc-2.15.so] - libc-start.c:226 __libc_start_main
0x76edea49 [ModemManager] + 0x00014a49
0x76eb4eab [ld-2.15.so] + 0x0000aeab
(cherry picked from commit be8c8a99bb29d340720715874696bc1fae11d331)
Change-Id: I5e80b77c313e1fbc10199c0d8fa17c3f1c7694e2
1 file changed
