[Bug 947041] Re: urandom startup script initializes poolsize with incorrect value

[Kasper Dupont]

I noticed another bug in the same script. The two calls of dd to save
the seed during boot and shutdown will truncate the pool before writing
new data. This will cause a small time window during which the seed only
exists in RAM and not on permanent storage. If the system was to crash
or lose power during that time window, all the entropy collected since
the system was first installed would be lost. Using conv=notrunc would
avoid this problem.

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https://bugs.launchpad.net/bugs/947041

Title:
  urandom startup script initializes poolsize with incorrect value

Status in “sysvinit” package in Ubuntu:
  New

Bug description:
  /etc/init.d/urandom compares the size of the saved pool in
  /var/lib/urandom/random-seed with the current value in
  /proc/sys/kernel/random/poolsize and updates the poolsize if it is too
  small. But when updating poolsize it uses the old value rather than
  the new value.

  Btw. The comment saying:
          # Hm, why is the saved pool re-created at boot? [pere 2009-09-03]
  should be replaced with:
          # The saved pool re-created at boot to ensure successive boots will use a different random seed, even if the system did not shut down cleanly.

  ProblemType: Bug
  DistroRelease: Ubuntu 10.04
  Package: initscripts 2.87dsf-4ubuntu17.4
  ProcVersionSignature: Ubuntu 2.6.32-37.81-generic 2.6.32.49+drm33.21
  Uname: Linux 2.6.32-37-generic i686
  Architecture: i386
  Date: Mon Mar  5 12:02:10 2012
  EcryptfsInUse: Yes
  InstallationMedia: Ubuntu 10.04.3 LTS "Lucid Lynx" - Release i386 (20110720.1)
  ProcEnviron:
   PATH=(custom, user)
   LANG=en_DK.utf8
   SHELL=/bin/bash
  SourcePackage: sysvinit

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