[Bug 1427600] Re: apport-unpack: ValueError: ['UserGroups'] has no binary content

[Nicholas Schell]

Latest fix filling in 'N/A' for absent groups is working, apport-unpack
is no longer throwing stacktrace when prcoessing the report. I still
don't understand why primary groups are ignored, but the important thing
is the reports are processable without errors now.

This might be a totally separate issue, but will it be possible to
backport the 'N/A' fix to bionic?

Reproduced by testing a user with a system group as their primary group
(will have N/A in report), this is equivalent to the user being in no
system groups (even though they are). Also a user which has an
additional group which is a system group (will show that system group in
report).

# system group to test with
sudo addgroup --system testgroup1

# create user with their primary group as the above system group (user doesn't have to be system user, just don't have to fill in gecos)
sudo adduser --system --ingroup testgroup1 testuser1
# create user with additional group as system group, their primary group in this case is nogroup
sudo adduser --system testuser2
sudo usermod -a -G testgroup1 testuser2

# run simple app as first user
sudo -u testuser1 /usr/bin/sleep 60000
# kill and create crash report
sudo pkill -SEGV -f '^/usr/bin/sleep 60000'
report="/var/crash/_usr_bin_sleep.$(id -u testuser1).crash"
# wait a bit while report is generated
sleep 2
# check resulting crash report, should print UserGroups: N/A
sudo grep -H 'UserGroups:' $report
# try apport-unpack
sudo apport-unpack $report /tmp/crash1

# reset and try with other user
rm "$report"
sudo -u testuser2 /usr/bin/sleep 60000
sudo pkill -SEGV -f '^/usr/bin/sleep 60000'
report="/var/crash/_usr_bin_sleep.$(id -u testuser2).crash"
sleep 2
# should print UserGroups: testgroup1
sudo grep -H 'UserGroups:' "$report"
sudo apport-unpack $report /tmp/crash2

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https://bugs.launchpad.net/bugs/1427600

Title:
  apport-unpack: ValueError: ['UserGroups'] has no binary content

Status in apport package in Ubuntu:
  Fix Released
Status in apport source package in Xenial:
  Triaged
Status in apport source package in Focal:
  Fix Committed
Status in apport source package in Groovy:
  Fix Released

Bug description:
  [Impact]
  apport-unpack crashes when trying to unpack a crash

  [Test Case]
  On a system running 20.04 LTS:
  1) create an additional user who is only a member of their own group e.g.
  bdmurray at clean-focal-amd64:~$ id crashy
  uid=1001(crashy) gid=1001(crashy) groups=1001(crashy)
  2) Launch a process as that user
  3) kill -11 that process
  4) Confirm there is a crash file in /var/crash for that process
  5) Run apport-unpack on that .crash file

  With the version of apport from -proposed you will not get another
  crash file when unpacking the crash file.

  [Regression Potential]
  We are just setting UserGroups to ' ' as opposed to having it be completely empty so there isn't any chance for regression. 

  When running apport-unpack to get at a core dump

  laney at raleigh> sudo apport-unpack _usr_lib_x86_64-linux-gnu_urfkill_urfkilld.0.crash ~/temp/zozoz
  [sudo] password for laney:
  Traceback (most recent call last):
    File "/usr/bin/apport-unpack", line 73, in <module>
      pr.extract_keys(f, bin_keys, dir)
    File "/usr/lib/python3/dist-packages/problem_report.py", line 253, in extract_keys
      [item for item, element in b64_block.items() if element is False])
  ValueError: ['UserGroups'] has no binary content
  laney at raleigh> apport-cli --version
  2.16.2

  It's not terrible, because most files are unpacked (those which sort
  before UserGroups, I guess).

  ProblemType: BugDistroRelease: Ubuntu 15.04
  Package: apport 2.16.2-0ubuntu1
  ProcVersionSignature: Ubuntu 3.19.0-7.7-generic 3.19.0
  Uname: Linux 3.19.0-7-generic x86_64
  ApportLog:

  ApportVersion: 2.16.2-0ubuntu1
  Architecture: amd64
  CurrentDesktop: Unity
  Date: Tue Mar  3 10:09:26 2015
  InstallationDate: Installed on 2012-10-07 (876 days ago)
  InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Beta amd64 (20121007)
  PackageArchitecture: allSourcePackage: apport
  UpgradeStatus: Upgraded to vivid on 2013-05-07 (665 days ago)

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