Private connection should be properly closed with dbus_connection_close
otherwise libdbus exits with the following error:
'The last reference on a connection was dropped without closing the
connection. This is a bug in an application. See
dbus_connection_unref() documentation for details. Most likely, the
application was supposed to call dbus_connection_close(), since this
is a private connection.'
This partially reverts 510b32b7156625b9df737c916b7a7a5c6fb285b9 since it
still necessary to take a reference before calling dbus_watch_handle
since internally it can call watch_info_free as in the following trace:
Invalid read of size 8
at 0x121085: watch_func (mainloop.c:105)
by 0x4C72694: g_main_context_dispatch (gmain.c:2539)
by 0x4C729C7: g_main_context_iterate.isra.23 (gmain.c:3146)
by 0x4C72DC1: g_main_loop_run (gmain.c:3340)
by 0x120541: main (main.c:551)
Address 0x5bbcd90 is 16 bytes inside a block of size 24 free'd
at 0x4A079AE: free (vg_replace_malloc.c:427)
by 0x4C7837E: g_free (gmem.c:252)
by 0x4F708BF: dbus_watch_set_data (dbus-watch.c:614)
by 0x4F70938: _dbus_watch_unref (dbus-watch.c:132)
by 0x4F6E9A7: _dbus_transport_handle_watch (dbus-transport.c:884)
by 0x4F59AFB: _dbus_connection_handle_watch (dbus-connection.c:1497)
by 0x4F70AF9: dbus_watch_handle (dbus-watch.c:683)
by 0x121084: watch_func (mainloop.c:103)
by 0x4C72694: g_main_context_dispatch (gmain.c:2539)
by 0x4C729C7: g_main_context_iterate.isra.23 (gmain.c:3146)
by 0x4C72DC1: g_main_loop_run (gmain.c:3340)
by 0x120541: main (main.c:551)
Commit abfc2b0dd5c3e33abfdf1a815b16d492c1751c06 attempted to fix a crash
related to improper reference counting, but the main issue was that the
reference was taken only during the function call (which is usually
unnecessary for single thread), but still passed a pointer to
DBusConnection to a function that is called by the mainloop. This left a
window where the DBusConnection can be destroyed.
Fixes this crash on unit/test-gdbus-client:
==32642== Invalid read of size 4
==32642== at 0x690D0A6: dbus_connection_ref (in
/lib/i386-linux-gnu/libdbus-1.so.3.7.6)
==32642== by 0x804CEDB: message_dispatch (mainloop.c:73)
==32642== by 0x684580E: g_timeout_dispatch (gmain.c:4450)
==32642== by 0x6844A75: g_main_context_dispatch (gmain.c:3065)
==32642== by 0x6844E14: g_main_context_iterate.isra.23 (gmain.c:3712)
==32642== by 0x68452FA: g_main_loop_run (gmain.c:3906)
==32642== by 0x804C7D3: client_connect_disconnect
(test-gdbus-client.c:188)
==32642== by 0x6868DB2: g_test_run_suite_internal (gtestutils.c:2067)
==32642== by 0x6868F8D: g_test_run_suite_internal (gtestutils.c:2138)
==32642== by 0x6869320: g_test_run_suite (gtestutils.c:2189)
==32642== by 0x686936B: g_test_run (gtestutils.c:1508)
==32642== by 0x696D4D2: (below main) (libc-start.c:226)
==32642== Address 0x709c6e4 is 140 bytes inside a block of size 144
free'd
==32642== at 0x67E806C: free (in
/usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==32642== by 0x692D62E: dbus_free (in
/lib/i386-linux-gnu/libdbus-1.so.3.7.6)
==32642== by 0x690E1C2: ??? (in
/lib/i386-linux-gnu/libdbus-1.so.3.7.6)
==32642== by 0x804AAEC: destroy_context (test-gdbus-client.c:104)
==32642== by 0x6868DB2: g_test_run_suite_internal (gtestutils.c:2067)
==32642== by 0x6868F8D: g_test_run_suite_internal (gtestutils.c:2138)
==32642== by 0x6869320: g_test_run_suite (gtestutils.c:2189)
==32642== by 0x686936B: g_test_run (gtestutils.c:1508)
==32642== by 0x696D4D2: (below main) (libc-start.c:226)
When getting disconnected from the bus sometimes (maybe always?)
dbus_watch_handle() can cause the "info" context to be free'd meaning
that we should not try to access it after the call. The only member we
need access to is the connection pointer and as the code already has a
ref() call for it it's only natural to solve the issue by adding a local
variable not dependent on "info".
The backtrace of the crash fixed looks as follows:
Invalid read of size 8
at 0x121085: watch_func (mainloop.c:105)
by 0x4C72694: g_main_context_dispatch (gmain.c:2539)
by 0x4C729C7: g_main_context_iterate.isra.23 (gmain.c:3146)
by 0x4C72DC1: g_main_loop_run (gmain.c:3340)
by 0x120541: main (main.c:551)
Address 0x5bbcd90 is 16 bytes inside a block of size 24 free'd
at 0x4A079AE: free (vg_replace_malloc.c:427)
by 0x4C7837E: g_free (gmem.c:252)
by 0x4F708BF: dbus_watch_set_data (dbus-watch.c:614)
by 0x4F70938: _dbus_watch_unref (dbus-watch.c:132)
by 0x4F6E9A7: _dbus_transport_handle_watch (dbus-transport.c:884)
by 0x4F59AFB: _dbus_connection_handle_watch (dbus-connection.c:1497)
by 0x4F70AF9: dbus_watch_handle (dbus-watch.c:683)
by 0x121084: watch_func (mainloop.c:103)
by 0x4C72694: g_main_context_dispatch (gmain.c:2539)
by 0x4C729C7: g_main_context_iterate.isra.23 (gmain.c:3146)
by 0x4C72DC1: g_main_loop_run (gmain.c:3340)
by 0x120541: main (main.c:551)
Address an issue in which the daemon incorrectly handles D-Bus main
loop timeouts by only removing timeouts that are not enabled when
D-Bus requests a timeout removal.
We where not dispatching data when a bus disconnects which cause
Disconnected signal to not be processed and thus causing the process to
either not exit or to not trigger callbacks registered with
g_dbus_set_disconnect_function.
To fix this now we always schedule a dispatch which will make sure data
still not processed will make its way to the proper handlers even if
disconnected.
Timeouts should also be removed in the remove_timeout callback in
addition to the timeout_handler_free function. This is how dbus-glib
does it and it seems to prevent crashes in certain situations.
Current implementation of libdbus Request name is blocking, consequently
the first incomming message that triggered the service autostart is not
being processed properly.
Luiz Augusto von Dentz
Anderson Lizardo
Johan Hedberg
Marcel Holtmann
Grant Erickson
Luiz Augusto von Dentz
Vinicius Costa Gomes
Forrest Zhao
Daniel Orstadius
Claudio Takahasi
Marcel Holtmann