1496991 - Native extension API leaks network connections to host binary

Status: RESOLVED DUPLICATE of bug 1452461

(WebExtensions :: General, defect)

Description

[Stefan Becker]

User Agent: Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:62.0) Gecko/20100101 Firefox/62.0

Steps to reproduce:

I tested the new browser integration in KDE Plasma 5.13 and noticed that the native host program seems to create outgoing network connections, although it shouldn't. After filing a bug upstream https://bugs.kde.org/show_bug.cgi?id=399449 a KDE developer on #plasma@freenode looked into the issue:

   (19:27:30) fvogt: Hm, it looks like it's a firefox bug
   (19:27:45) fvogt: The connections are listed as opened by pbi as firefox leaked some socket fds into the process
   (19:28:21) fvogt: Oh, yeah
   (19:28:31) fvogt: Firefox doesn't use O_CLOEXEC in many places
   (19:28:59) _stefanb: could you fix it in the host part?
   (19:29:11) fvogt: We could work around it, yes
   (19:29:33) fvogt: Please file a bug report upstream at firefox though

The leakage would also explain why the connections are listed as CLOSE_WAIT, because nobody is closing the leaked fds.

Platform: Fedora 29, Linux, x86_64
$ rpm -q firefox plasma-browser-integration
firefox-62.0-3.fc29.x86_64
plasma-browser-integration-5.13.5-1.fc29.x86_64



Actual results:

Snapshot from my test system:

$ netstat -tnp | fgrep -e plasma- -e firefox
tcp        0      0 192.168.3.6:39846        xxxx:443       ESTABLISHED 1753/firefox
tcp        0      0 192.168.3.6:33556        xxxx:443       ESTABLISHED 1753/firefox
... many more open connections from firefox ....
tcp   2194537      0 192.168.3.6:49664       xxxx:443       ESTABLISHED 1753/firefox

tcp        1      0 192.168.3.6:35696       104.16.111.25:443       CLOSE_WAIT  2686/plasma-browser
tcp       32      0 192.168.3.6:57386       151.101.193.69:443      CLOSE_WAIT  2686/plasma-browser
...
tcp     8692      0 192.168.3.6:50810       104.20.117.11:443       CLOSE_WAIT  2686/plasma-browser

$ ps -efw | fgrep 2686
stefanb   2686  1753  0 09:38 ?        00:00:00 /usr/bin/plasma-browser-integration-host /usr/lib64/mozilla/native-messaging-hosts/org.kde.plasma.browser_integration.json [e-mail]


Expected results:

Firefox should not leak open file descriptors to the native extension program.

Comment 1

[Stefan Becker]

I tried the workaround from https://phabricator.kde.org/D15984 and now I don't see any outgoing network connections from pbi anymore. The analysis of the KDE developer therefore is correct: firefox leaks open fds when exec()'ing the native host binary.