• Ting-Wei Lan's avatar
    gtestdbus: Fix watcher crash on FreeBSD · 91474038
    Ting-Wei Lan authored
    In file gio/gtestdbus.c, function watch_parent, there is a loop which
    waits for commands sent from the parent process and kills all processes
    recorded in 'pids_to_kill' array on parent process exit. The detection
    of parent process exit is done by calling g_poll and checking whether
    the returned event is G_IO_HUP. However, 'revents' is a bit mask, and
    we should use a bitwise-AND check instead of the equality check here.
    
    It seems to work fine on Linux, but it fails on FreeBSD because the
    g_poll returns both G_IO_IN and G_IO_HUP on pipe close. This means the
    watcher process continues waiting for commands after the parent process
    exit, and g_io_channel_read_line returns G_IO_STATUS_EOF with 'command'
    set to NULL. Then the watcher process crashes with segfault when calling
    sscanf because 'command' is NULL. Since the test result is already
    reported by the parent process as 'OK', this kind of crash is likely to
    be unnoticed unless someone checks dmesg messages after the test:
    
    pid 57611 (defaultvalue), uid 1001: exited on signal 11
    pid 57935 (actions), uid 1001: exited on signal 11
    pid 57945 (gdbus-bz627724), uid 1001: exited on signal 11
    pid 57952 (gdbus-connection), uid 1001: exited on signal 11
    pid 57970 (gdbus-connection-lo), uid 1001: exited on signal 11
    pid 57976 (gdbus-connection-sl), uid 1001: exited on signal 11
    pid 58039 (gdbus-exit-on-close), uid 1001: exited on signal 11
    pid 58043 (gdbus-exit-on-close), uid 1001: exited on signal 11
    pid 58047 (gdbus-exit-on-close), uid 1001: exited on signal 11
    pid 58051 (gdbus-exit-on-close), uid 1001: exited on signal 11
    pid 58055 (gdbus-export), uid 1001: exited on signal 11
    pid 58059 (gdbus-introspection), uid 1001: exited on signal 11
    pid 58065 (gdbus-names), uid 1001: exited on signal 11
    pid 58071 (gdbus-proxy), uid 1001: exited on signal 11
    pid 58079 (gdbus-proxy-threads), uid 1001: exited on signal 11
    pid 58083 (gdbus-proxy-well-kn), uid 1001: exited on signal 11
    pid 58091 (gdbus-test-codegen), uid 1001: exited on signal 11
    pid 58095 (gdbus-threading), uid 1001: exited on signal 11
    pid 58104 (gmenumodel), uid 1001: exited on signal 11
    pid 58108 (gnotification), uid 1001: exited on signal 11
    pid 58112 (gdbus-test-codegen-), uid 1001: exited on signal 11
    pid 58116 (gapplication), uid 1001: exited on signal 11
    pid 58132 (dbus-appinfo), uid 1001: exited on signal 11
    
    If the watcher process crashes before killing the dbus-daemon process
    spawned by the parent process, the dbus-daemon process will keep running
    after all tests complete. Due to the implementation of 'communicate'
    function in Python subprocess, it causes meson to crash. 'communicate'
    assumes the stdout and stderr pipes are closed when the child process
    exits, but it is not true if processes forked by the child process
    doesn't exit. It causes Python subprocess 'communicate' function to
    block on the call to poll until the timeout expires even if the test
    finishes in a few seconds. Meson assumes the timeout exception always
    means the test is still running. It calls 'communicate' again and
    crashes because pipes no longer exist.
    
    Infrastructure/GitLab#286
    https://github.com/mesonbuild/meson/issues/3967
    https://bugs.python.org/issue30154
    91474038
gtestdbus.c 22.6 KB