desktop-packages team mailing list archive

[Tyler Hicks <tyhicks@xxxxxxxxxxxxx>]

This turned out to be a tricky one. It is definitely an eCryptfs bug.
The upstream fix that I thought would solve this issue ended up not
being the right fix. Instead, it turned out to be the following two
commits:

bd4f0fe8bb7c73c738e1e11bc90d6e2cf9c6e20e
fed8859b3ab94274c986cbdf7d27130e0545f02c

However, I didn't write those patches as bug fixes. I was simply
cleaning out some crufty looking code. It turned out to be buggy code,
too.

Creating a file, extending that file, the file's pages being reclaimed,
finally followed by reading the file is what triggers this. In the case
of this bug report, the system being under memory pressure is what
forced the file's pages out of the page cache.

The easiest way to reproduce the bug is with the following shell
commands:

$ touch foo && truncate -s 4096 foo && sync && echo 1 | sudo tee
/proc/sys/vm/drop_caches && hexdump -C foo

hexdump should show a file filled with zeroes, but it doesn't.

Data corruption is a possibility if the file is written to before the
eCryptfs directory is unmounted.

It looks like all kernels before 2.6.39 are affected, possibly all the
way back to the beginning of eCryptfs being merged upstream. Patch, with
all the technical eCryptfs details in the commit message, to follow...

-- 
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Packages, which is subscribed to libreoffice in Ubuntu.
https://bugs.launchpad.net/bugs/745836

Title:
  encrypted swap corrupts application stack/heap [was: soffice.bin
  SIGSEGV cppu::throwException()]

Status in LibreOffice Productivity Suite:
  Won't Fix
Status in “ecryptfs-utils” package in Ubuntu:
  Invalid
Status in “libreoffice” package in Ubuntu:
  Invalid
Status in “linux” package in Ubuntu:
  Fix Released
Status in “openoffice.org” package in Ubuntu:
  Won't Fix
Status in “ecryptfs-utils” source package in Maverick:
  Invalid
Status in “libreoffice” source package in Maverick:
  Invalid
Status in “linux” source package in Maverick:
  Confirmed
Status in “openoffice.org” source package in Maverick:
  Won't Fix
Status in “ecryptfs-utils” source package in Natty:
  Invalid
Status in “libreoffice” source package in Natty:
  Invalid
Status in “linux” source package in Natty:
  Confirmed
Status in “openoffice.org” source package in Natty:
  Won't Fix
Status in “ecryptfs-utils” source package in Oneiric:
  Invalid
Status in “libreoffice” source package in Oneiric:
  Invalid
Status in “linux” source package in Oneiric:
  Fix Released
Status in “openoffice.org” source package in Oneiric:
  Won't Fix

Bug description:
  Binary package hint: libreoffice

  1) lsb_release -rd
  Description:	Ubuntu 11.04
  Release:	11.04

  2) apt-cache policy libreoffice-calc
  libreoffice-calc:
    Installed: 1:3.3.3-1ubuntu2
    Candidate: 1:3.3.3-1ubuntu2
    Version table:
   *** 1:3.3.3-1ubuntu2 0
          100 /var/lib/dpkg/status
       1:3.3.2-1ubuntu5 0
          500 http://us.archive.ubuntu.com/ubuntu/ natty-updates/main i386 Packages
       1:3.3.2-1ubuntu4 0
          500 http://us.archive.ubuntu.com/ubuntu/ natty/main i386 Packages

  apt-cache policy libreoffice-writer
  libreoffice-writer:
    Installed: 1:3.3.3-1ubuntu2
    Candidate: 1:3.3.3-1ubuntu2
    Version table:
   *** 1:3.3.3-1ubuntu2 0
          100 /var/lib/dpkg/status
       1:3.3.2-1ubuntu5 0
          500 http://us.archive.ubuntu.com/ubuntu/ natty-updates/main i386 Packages
       1:3.3.2-1ubuntu4 0
          500 http://us.archive.ubuntu.com/ubuntu/ natty/main i386 Packages

  3) What is expected to happen in a KDE Natty in a KDE session with the
  KDE integration active or GNOME is a Writer or Calc file untouched for
  a long period of time (ex. 1 hour+) is when one tries to edit it, the
  application does not crash.

  4) What happens instead is it crashes. This is highly correlated to
  both EcryptfsInUse and resource constrained (Memory & CPU >> 50%)
  environments. Occurs with:

  + Intel drivers, Compiz not enabled, Writer open only bug 745836
  + binary ATI drivers, Compiz enabled, Calc open only bug 799047

  ProblemType: Crash
  DistroRelease: Ubuntu 11.04
  Package: libreoffice-core 1:3.3.2-1ubuntu2
  ProcVersionSignature: Ubuntu 2.6.38-7.39-generic 2.6.38
  Uname: Linux 2.6.38-7-generic i686
  Architecture: i386
  Date: Wed Mar 30 12:34:39 2011
  Disassembly: => 0x100000:	Cannot access memory at address 0x100000
  EcryptfsInUse: Yes
  ExecutablePath: /usr/lib/libreoffice/program/soffice.bin
  ProcCmdline: /usr/lib/libreoffice/program/soffice.bin -writer -splash-pipe=5
  ProcEnviron:
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SegvAnalysis:
   Segfault happened at: 0x100000:	Cannot access memory at address 0x100000
   PC (0x00100000) not located in a known VMA region (needed executable region)!
  SegvReason: executing unknown VMA
  Signal: 11SourcePackage: libreoffice
  StacktraceTop:
   ?? ()
   cppu::throwException(com::sun::star::uno::Any const&) () from /usr/lib/libreoffice/program/../basis-link/program/../ure-link/lib/libuno_cppuhelpergcc3.so.3
   ucbhelper::cancelCommandExecution(com::sun::star::ucb::IOErrorCode, com::sun::star::uno::Sequence<com::sun::star::uno::Any> const&, com::sun::star::uno::Reference<com::sun::star::ucb::XCommandEnvironment> const&, rtl::OUString const&, com::sun::star::uno::Reference<com::sun::star::ucb::XCommandProcessor> const&) () from /usr/lib/libreoffice/program/../basis-link/program/libucbhelper4gcc3.so
   ?? () from /usr/lib/libreoffice/program/../basis-link/program/libucpfile1.so
   ?? () from /usr/lib/libreoffice/program/../basis-link/program/libucpfile1.so
  Title: soffice.bin crashed with SIGSEGV in cppu::throwException()UpgradeStatus: Upgraded to natty on 2011-03-29 (0 days ago)
  UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare

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