[Bug 1016040] Re: apt_check.py crashed with SIGSEGV in FileName()

[James Hunt]

I have not yet been able to reproduce this, but the stack trace is
suggestive of either memory corruption or a pointer walking beyond the
end of a list.

Consider a few choice entries from the 'stat' buffer shown in
debPackagesIndex::FindInCache in the stacktrace:

st_nlink = 0 (impossible)
st_blksize = 0 (impossible)
tv_sec = 140058388787402 (eermmm)
st_uid = 32609 (expected st_uid=0)
st_gid = 1 (expected st_gid=0)

These values are either impossible or highly unlikely.

Is this repeatable if a non-privileged user runs the check that is failing?:
 
    /usr/bin/python /usr/lib/update-notifier/apt-check

It would also be useful to see the output of:

    apt-config dump

I do wonder if this issue was caused due to 'srcpkgcache.bin' being
updated at the time /usr/lib/update-notifier/apt-check ran.

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https://bugs.launchpad.net/bugs/1016040

Title:
  apt_check.py crashed with SIGSEGV in FileName()

Status in “apt” package in Ubuntu:
  Confirmed
Status in “apt” source package in Quantal:
  Confirmed

Bug description:
  after dist-upgrade this morning -- popped up after rebooting out of
  kernel 3.5 back into 3.4.

  ProblemType: Crash
  DistroRelease: Ubuntu 12.10
  Package: update-notifier-common 0.119ubuntu13
  ProcVersionSignature: Ubuntu 3.4.0-5.11-generic 3.4.0
  Uname: Linux 3.4.0-5-generic x86_64
  ApportVersion: 2.2.4-0ubuntu1
  Architecture: amd64
  CheckboxSubmission: c8a7d84e13c3b258e707f056604eb0e0
  CheckboxSystem: d00f84de8a555815fa1c4660280da308
  Date: Thu Jun 21 08:10:17 2012
  ExecutablePath: /usr/lib/update-notifier/apt_check.py
  InterpreterPath: /usr/bin/python2.7
  PackageArchitecture: all
  ProcCmdline: /usr/bin/python /usr/lib/update-notifier/apt-check
  SegvAnalysis:
   Segfault happened at: 0x7f61e282e3c7 <_ZNK16debPackagesIndex11FindInCacheER8pkgCache+407>:	mov    0x0(%rbp),%esi
   PC (0x7f61e282e3c7) ok
   source "0x0(%rbp)" (0x7f6220fae470) not located in a known VMA region (needed readable region)!
   destination "%esi" ok
  SegvReason: reading unknown VMA
  Signal: 11
  SourcePackage: update-notifier
  StacktraceTop:
   debPackagesIndex::FindInCache(pkgCache&) const () from /usr/lib/x86_64-linux-gnu/libapt-pkg.so.4.12
   ?? () from /usr/lib/x86_64-linux-gnu/libapt-pkg.so.4.12
   pkgCacheGenerator::MakeStatusCache(pkgSourceList&, OpProgress*, MMap**, bool) () from /usr/lib/x86_64-linux-gnu/libapt-pkg.so.4.12
   pkgCacheFile::BuildCaches(OpProgress*, bool) () from /usr/lib/x86_64-linux-gnu/libapt-pkg.so.4.12
   pkgCacheFile::Open(OpProgress*, bool) () from /usr/lib/x86_64-linux-gnu/libapt-pkg.so.4.12
  Title: apt_check.py crashed with SIGSEGV in debPackagesIndex::FindInCache()
  UpgradeStatus: Upgraded to quantal on 2012-06-16 (4 days ago)
  UserGroups: adm admin cdrom dialout kismet kvm libvirtd lpadmin plugdev sambashare sudo vboxusers wireshark
  modified.conffile..etc.apt.apt.conf.d.10periodic:
   APT::Periodic::Update-Package-Lists "1";
   APT::Periodic::Download-Upgradeable-Packages "1";
   APT::Periodic::AutocleanInterval "0";
  mtime.conffile..etc.apt.apt.conf.d.10periodic: 2011-08-30T18:25:25.247774

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