connman_ncurses crashes when toggling between online/offline modes

[javier-lopez]

Testcase:

1. Execute connman_ncurses
2. Press 'o' on an available technology (tested only for wifi)
3. The status is toggle, the network is shutdown or configured but connman_ncurses crashes.

libjson-c2 version 0.11-3. I don't know enough C, but anyway went on and tried to debug by myself without success =)

(gdb) bt
#0  0x00007ffff77752b0 in printbuf_reset () from /lib/x86_64-linux-gnu/libjson-c.so.2
#1  0x00007ffff777158e in json_object_to_json_string_ext () from /lib/x86_64-linux-gnu/libjson-c.so.2
#2  0x00000000004093b1 in __renderers_state (jobj=0x618e40) at renderers.c:237
#3  0x0000000000409534 in __renderers_home_page (jobj=0x6482d0) at renderers.c:271
#4  0x000000000040d175 in action_on_cmd_callback (jobj=0x648590) at main.c:475
#5  0x000000000040e039 in main_callback (status=0, jobj=0x648590) at main.c:831
#6  0x000000000040761d in get_home_page (jobj=0x0) at engine.c:353
#7  0x00000000004088eb in engine_query (jobj=0x647c40) at engine.c:964
#8  0x000000000040e1fe in print_home_page () at main.c:882
#9  0x000000000040cdc7 in exec_refresh () at main.c:362
#10 0x000000000040d46e in action_on_signal (jobj=0x643b10) at main.c:559
#11 0x000000000040e053 in main_callback (status=12345, jobj=0x643b10) at main.c:834
#12 0x00000000004080ff in engine_commands_sig (jobj=0x643b10) at engine.c:765
#13 0x0000000000405476 in monitor_changed (connection=0x616c30, message=0x618710, user_data=0x0) at commands.c:622
#14 0x00007ffff7ba4ad6 in dbus_connection_dispatch () from /lib/x86_64-linux-gnu/libdbus-1.so.3
#15 0x0000000000406dc9 in loop_run (poll_stdin=true) at loop.c:194
#16 0x000000000040f7ad in main () at main.c:1554

[jobol]

Thanks for the report.

It should work with json-c 0.11 thus there is no problem of version with json-c. What version of connman are you using?

We should check but it can take time.

Is there a work around?

[javier-lopez]

I was able to reproduce this with the latest connman git version and connman 1.27, haven't tried with lower versions. I've not found any workaround but will keep poking it.

[alan-mushi]

Hi,

I was able to reproduce the bug on debian with the connmand packaged and the latest git version. connman_ncurses don't crash every time, often it just keep hanging on "Toggling OfflineMode..." after at least 3 offline/online toggling.

@chilicuil when it crashes do you see "junk" string for State and OfflineMode in the header ? By junk string I mean some random JSON string that shouldn't be there, for example I have State: wifi and OfflineMode: [ "Pow....

This far I found that the jobj argument for __renderers_state() causes a segfault when I try to print it (as well as state and offline_mode variables). I was able to trace back the faulty object back to state in engine.c. I can't investigate more right away but I will do as soon as possible (e.g. one weekend).

[javier-lopez]

Hello Alan,

Yes, I also see garbage strings in the headers, exactly the same text, State: wifi OfflineMode: [ "Pow

[alan-mushi]

So I solved this: In engine.c react_to_sig_manager() (line 865), the state is updated with a pointer to the data to print but I forgot to increment the refcount of the aforementioned data.

@jobol Do you prefer a pull request or a commit to fix this ?

I'm sorry I missed it.

[jobol]

@alan-mushi to be honest, I prefer a pull request linked to that issue (#2) but the operation is really painful to do. That script is doing that:

#!/bin/bash

usage() {
    echo "usage: $(basename $0) nick repo issue [brsrc [brtgt]]"
}

case $# in
    3) nick=$1; repo=$2; issue=$3; brsrc=issue$3; brtgt=master;;
    4) nick=$1; repo=$2; issue=$3; brsrc=$4; brtgt=master;;
    5) nick=$1; repo=$2; issue=$3; brsrc=$4; brtgt=$5;;
    *) usage >&2; exit 1;;
esac

cat << EOC
curl \
    --user $nick \
    --request POST \
    --data '{"issue": "$issue", "head": "$nick:$brsrc", "base": "$brtgt"}' \
    https://api.github.com/repos/$repo/pulls
EOC

By typing

  script alan-mushi connman-json-client 2

You will get the REST API pull request for attaching the commit to the issue

[alan-mushi]

PS: there might be a better solution than the script : https://github.com/blog/1506-closing-issues-via-pull-requests

[jobol]

When I tried what you suggest, it failed. So do it as you want. Let's try...

[alan-mushi]

I got an issue (404 HTTP code) with your script for the api url see https://developer.github.com/v3/pulls/#create-a-pull-request for the new url format.

[jobol]

I'll update my script, thanks