Hello.
Some days ago, Firefox unexpectedly has been closed after a couple of hours (mostly viewed: YouTube and some other websites). Next, a dialog box related to the Mozilla Crash Reporter appeared - with message, that reporter is disabled (which I did earlier via 'about:config' and *datareporting.healthreport.service.enabled* key set to _false_) and no crash report is available even via 'about:crashes' etc.
After this situation two entries appeared in the log files: first related to the AppArmor and second: plugin-container segfault. By the way: in the same time there was an update for flash-plugin available (see: 1).
Anyway, 'LastCrash' file (which can be found in ~/.mozilla/firefox/Crash Reports/ directory) contains only: 1484142985. Just like all the others files in this directory. There are also two folders called: 'events' and 'pending'. But they are completely empty. However, system log files, such as '/var/log/kern.log' or '/var/log/syslog', contains an interesting entries:
● Jan 11 14:56:25 t4 kernel: [ 4161.295639] type=1400 audit(1484142985.517:46): apparmor="DENIED" operation="open" parent=2818 profile="/usr/lib/firefox/firefox{,*[^s][^h]}" name="/proc/2818/task/" pid=3253 comm="firefox" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000
● Jan 11 14:56:25 t4 kernel: [ 4161.540727] Chrome_ChildThr[2890]: segfault at 0 ip b76df673 sp b1efe9f0 error 6 in plugin-container[b76d8000+42000]
As we know, thanks to the plugin-container, plugins are separated from the browser process, making it more stable, right? So now if a plugin crashes, Firefox should remains unharmed. It looks like this is a known problem (see: 2, 3).
By the way; on Moday, 16 January, Firefox has been closed again - no action from my side. Log files contain the same entries as above:
● Jan 16 16:39:35 t4 kernel: [14373.711834] type=1400 audit(1484581175.931:48): apparmor="DENIED" operation="open" parent=2532 profile="/usr/lib/firefox/firefox{,*[^s][^h]}" name="/proc/2532/task/" pid=3389 comm="firefox" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000
● Jan 16 16:39:36 t4 kernel: [14373.934394] Chrome_ChildThr[3041]: segfault at 0 ip b76f8673 sp b1efe9f0 error 6 in plugin-container[b76f1000+42000]
Anyway, after adding these two rules to the Firefox profile, everything seems to be OK and there is not DENIED message for "/proc/*/task/" entry anymore (so the first issue is solved):
owner @{PROC}/[0-9]*/task/ r,
owner @{PROC}/[0-9]*/task/* r,
NOTE: This problem occurs when adobe-flash plugin is not activated and is permanently disabled and also when is used/enabled. Here are some informations about versions etc.:
● Firefox: 50.1.0
● Flash: 24.0.0.194ubuntu0.12.04.1
● Linux: 3.2.0-120-generic-pae (3.2.79) i686
● AppArmor: 2.7.102-0ubuntu3.10
● Release: 12.04.5 LTS (via `lsb_release -a` command)
Best regards.
_____________
[1] https://lists.ubuntu.com/archives/precise-changes/2017-January/026047.html
[2] https://bugzilla.mozilla.org/show_bug.cgi?id=1205199
[3] https://bugzilla.redhat.com/show_bug.cgi?id=1253086
Status changed to 'Confirmed' because the bug affects multiple users.