[Bug 1795696] Re: /usr/bin/unattended-upgrade:UnboundLocalError:/usr/bin/unattended-upgrade at 1991:main:do_auto_remove

[Balint Reczey]

** Description changed:

+ [Impact]
+ 
+  * Unattended-upgrades crashes while auto-removing kernel packages.
+ 
+ [Test Case]
+ 
+ 1. Install kernel packages to be automatically removed:
+  #  eatmydata apt install linux-image-unsigned-4.18.0-13-generic linux-image-unsigned-4.18.0-14-generic linux-image-unsigned-4.18.0-15-generic
+  # apt-mark auto linux-image-unsigned-4.18.0-13-generic linux-image-unsigned-4.18.0-14-generic linux-image-unsigned-4.18.0-15-generic
+  #  /etc/kernel/postinst.d/apt-auto-removal
+ 
+ 2. Set up u-u to perform action in non-minimal steps:
+ # grep Minimal /etc/apt/apt.conf.d/50unattended-upgrades 
+ Unattended-Upgrade::MinimalSteps "false";
+ 
+ 3. Run u-u in dry-run mode.
+    Observe it failing with not fixed versions:
+   # unattended-upgrade --dry-run
+ Traceback (most recent call last):
+   File "/usr/bin/unattended-upgrade", line 1998, in <module>
+     sys.exit(main(options))
+   File "/usr/bin/unattended-upgrade", line 1798, in main
+     options.verbose or options.debug, options.dry_run)
+   File "/usr/bin/unattended-upgrade", line 1495, in do_auto_remove
+     if res:
+ UnboundLocalError: local variable 'res' referenced before assignment
+ 
+   Observe the fixed version running properly:
+  # ./unattended-upgrade --dry-run 
+  #
+ 
+ 
+ [Regression Potential] 
+ 
+  * The fix is very small and isolated, but a programming error could
+ cause the misreporting of the success of auto-removals. Considering the
+ size and simplicity of the change, regressions here seem unlikely.
+ 
+ 
+ [Original Bug Text]
+ 
+ 
  The Ubuntu Error Tracker has been receiving reports about a problem regarding unattended-upgrades.  This problem was most recently seen with package version 1.1ubuntu1.18.04.5, the problem page at https://errors.ubuntu.com/problem/651a7b7a070dd794d8cf2f5ea8e974614fdedb8e contains more details, including versions of packages affected, stacktrace or traceback, and individual crash reports.
  If you do not have access to the Ubuntu Error Tracker and are a software developer, you can request it at http://forms.canonical.com/reports/.

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https://bugs.launchpad.net/bugs/1795696

Title:
  /usr/bin/unattended-upgrade:UnboundLocalError:/usr/bin/unattended-
  upgrade at 1991:main:do_auto_remove

Status in unattended-upgrades package in Ubuntu:
  Fix Released
Status in unattended-upgrades source package in Xenial:
  New
Status in unattended-upgrades source package in Bionic:
  Confirmed
Status in unattended-upgrades source package in Cosmic:
  Fix Released

Bug description:
  [Impact]

   * Unattended-upgrades crashes while auto-removing kernel packages.

  [Test Case]

  1. Install kernel packages to be automatically removed:
   #  eatmydata apt install linux-image-unsigned-4.18.0-13-generic linux-image-unsigned-4.18.0-14-generic linux-image-unsigned-4.18.0-15-generic
   # apt-mark auto linux-image-unsigned-4.18.0-13-generic linux-image-unsigned-4.18.0-14-generic linux-image-unsigned-4.18.0-15-generic
   #  /etc/kernel/postinst.d/apt-auto-removal

  2. Set up u-u to perform action in non-minimal steps:
  # grep Minimal /etc/apt/apt.conf.d/50unattended-upgrades 
  Unattended-Upgrade::MinimalSteps "false";

  3. Run u-u in dry-run mode.
     Observe it failing with not fixed versions:
    # unattended-upgrade --dry-run
  Traceback (most recent call last):
    File "/usr/bin/unattended-upgrade", line 1998, in <module>
      sys.exit(main(options))
    File "/usr/bin/unattended-upgrade", line 1798, in main
      options.verbose or options.debug, options.dry_run)
    File "/usr/bin/unattended-upgrade", line 1495, in do_auto_remove
      if res:
  UnboundLocalError: local variable 'res' referenced before assignment

    Observe the fixed version running properly:
   # ./unattended-upgrade --dry-run 
   #

  
  [Regression Potential] 

   * The fix is very small and isolated, but a programming error could
  cause the misreporting of the success of auto-removals. Considering
  the size and simplicity of the change, regressions here seem unlikely.

  
  [Original Bug Text]

  
  The Ubuntu Error Tracker has been receiving reports about a problem regarding unattended-upgrades.  This problem was most recently seen with package version 1.1ubuntu1.18.04.5, the problem page at https://errors.ubuntu.com/problem/651a7b7a070dd794d8cf2f5ea8e974614fdedb8e contains more details, including versions of packages affected, stacktrace or traceback, and individual crash reports.
  If you do not have access to the Ubuntu Error Tracker and are a software developer, you can request it at http://forms.canonical.com/reports/.

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