[Bug 1567540] [NEW] ntpd crashed with SIGABRT (was: ntp crashes everytime the network goes up or down.)

Mon Aug 1 11:25:30 UTC 2016

You have been subscribed to a public bug by ChristianEhrhardt (paelzer):

[Impact]

 * In NTP 4.2.8p4 there are several races that can cause a crash on 
   startup or on a bit later but still on startup by DNS querying a 
   peer.

 * The crash obviously affects users, especially as it seems - due to 
   its racy nature - not appear on most, but severely hamstring some 
   other users.

 * The details are a bit blurred, but overall there were four fixes 
   upstream that address just this "kind of issue" that seemed to
   surface post 4.2.8p4.

[Test Case]

 * Start NTP (service)

 * Expectation: work

 * Failure: Crash

 * Constraints: this is a race, it seems to appear at <0.1% chance to 
   all systems I have (or lower - as I just can say it didn't trigger in 
   1000 tests). But that matches other reports. OTOH for some systems it 
   seems to trigger >50% which also matches the high amount of crash 
   reports (close to 20k now) as referred in comment 43

[Regression Potential]

 * Eventually the change is rather invasive as it changes the locking 
   scheme of parts of the code - so there surely is some regression 
   potential.

 * Fortunately not all, but most of this change is upstream and tested 
   quite heavily a few months already.

 * I tested as good as I could and could neither in code nor in test 
   find an obvious weakness, and looking at all the crash reports it is 
   about time.

[Other Info]

 * While all study of bugs, upstream changes and tests suggest we 
   haven't broken anything, still I have to admit that "on my own" I 
   can't confirm that it fixed the bug. So we are really dependent on 
   the reporters here that seem to have the kind of hardware where it 
   "crashes reliably".

--------

ntp crashes every time the network goes up or down while the system is running and also crashes after booting up without network.
---
ApportVersion: 2.20.1-0ubuntu1
Architecture: amd64
CurrentDesktop: XFCE
DistroRelease: Ubuntu 16.04
InstallationDate: Installed on 2016-03-12 (26 days ago)
InstallationMedia: Xubuntu 16.04 LTS "Xenial Xerus" - Alpha amd64 (20160224)
NtpStatus: ntpq: read: Connection refused
Package: ntp 1:4.2.8p4+dfsg-3ubuntu4
PackageArchitecture: amd64
ProcCmdline: BOOT_IMAGE=/boot/vmlinuz-4.4.0-17-generic root=UUID=306314bc-efcb-4c2d-b0e9-e05ec92ed0f0 ro
ProcVersionSignature: Ubuntu 4.4.0-17.33-generic 4.4.6
Tags:  xenial
Uname: Linux 4.4.0-17-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
---
ApportVersion: 2.20.1-0ubuntu1
Architecture: amd64
CurrentDesktop: XFCE
DistroRelease: Ubuntu 16.04
InstallationDate: Installed on 2016-03-12 (31 days ago)
InstallationMedia: Xubuntu 16.04 LTS "Xenial Xerus" - Alpha amd64 (20160224)
NtpStatus: ntpq: read: Connection refused
Package: ntp 1:4.2.8p4+dfsg-3ubuntu5
PackageArchitecture: amd64
ProcCmdline: BOOT_IMAGE=/boot/vmlinuz-4.4.0-18-generic root=UUID=306314bc-efcb-4c2d-b0e9-e05ec92ed0f0 ro
ProcVersionSignature: Ubuntu 4.4.0-18.34-generic 4.4.6
Tags:  xenial
Uname: Linux 4.4.0-18-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
---
ApportVersion: 2.20.1-0ubuntu1
Architecture: amd64
CurrentDesktop: XFCE
DistroRelease: Ubuntu 16.04
InstallationDate: Installed on 2016-04-13 (0 days ago)
InstallationMedia: Xubuntu 16.04 LTS "Xenial Xerus" - Beta amd64 (20160412)
NtpStatus: ntpq: read: Connection refused
Package: ntp 1:4.2.8p4+dfsg-3ubuntu5
PackageArchitecture: amd64
ProcCmdline: BOOT_IMAGE=/boot/vmlinuz-4.4.0-18-generic root=UUID=13f57794-2e19-4a56-836a-94185bba5ec5 ro quiet splash
ProcVersionSignature: Ubuntu 4.4.0-18.34-generic 4.4.6
Tags:  xenial
Uname: Linux 4.4.0-18-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
---
ApportVersion: 2.20.1-0ubuntu1
Architecture: amd64
CurrentDesktop: XFCE
DistroRelease: Ubuntu 16.04
InstallationDate: Installed on 2016-04-13 (0 days ago)
InstallationMedia: Xubuntu 16.04 LTS "Xenial Xerus" - Beta amd64 (20160412)
NtpStatus: ntpq: read: Connection refused
Package: ntp 1:4.2.8p4+dfsg-3ubuntu5
PackageArchitecture: amd64
ProcCmdline: BOOT_IMAGE=/boot/vmlinuz-4.4.0-18-generic root=UUID=13f57794-2e19-4a56-836a-94185bba5ec5 ro quiet splash
ProcVersionSignature: Ubuntu 4.4.0-18.34-generic 4.4.6
Tags:  xenial
Uname: Linux 4.4.0-18-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
---
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
CurrentDesktop: XFCE
DistroRelease: Ubuntu 16.04
InstallationDate: Installed on 2016-04-14 (3 days ago)
InstallationMedia: Xubuntu 16.04 LTS "Xenial Xerus" - Beta amd64 (20160412)
NtpStatus: ntpq: read: Connection refused
Package: ntp 1:4.2.8p4+dfsg-3ubuntu5
PackageArchitecture: amd64
ProcCmdline: BOOT_IMAGE=/boot/vmlinuz-4.4.0-20-generic root=UUID=b9c0528f-e81f-4b08-9b31-032f14f72ccd ro quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 4.4.0-20.36-generic 4.4.6
Tags:  xenial
Uname: Linux 4.4.0-20-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
---
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
CurrentDesktop: XFCE
DistroRelease: Ubuntu 16.04
InstallationDate: Installed on 2016-04-14 (3 days ago)
InstallationMedia: Xubuntu 16.04 LTS "Xenial Xerus" - Beta amd64 (20160412)
NtpStatus: ntpq: read: Connection refused
Package: ntp 1:4.2.8p4+dfsg-3ubuntu5
PackageArchitecture: amd64
ProcCmdline: BOOT_IMAGE=/boot/vmlinuz-4.4.0-20-generic root=UUID=b9c0528f-e81f-4b08-9b31-032f14f72ccd ro quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 4.4.0-20.36-generic 4.4.6
Tags:  xenial
Uname: Linux 4.4.0-20-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
---
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CurrentDesktop: XFCE
DistroRelease: Ubuntu 16.04
InstallationDate: Installed on 2016-04-14 (63 days ago)
InstallationMedia: Xubuntu 16.04 LTS "Xenial Xerus" - Beta amd64 (20160412)
NtpStatus: ntpq: read: Connection refused
Package: ntp 1:4.2.8p4+dfsg-3ubuntu5
PackageArchitecture: amd64
ProcCmdline: BOOT_IMAGE=/boot/vmlinuz-4.4.0-25-generic root=UUID=3aea4570-4011-4247-9636-68317385324d ro
ProcVersionSignature: Ubuntu 4.4.0-25.44-generic 4.4.13
Tags: xenial third-party-packages
Uname: Linux 4.4.0-25-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dialout dip lpadmin mail netdev plugdev sambashare sudo
_MarkForUpload: True

** Affects: ntp
     Importance: High
         Status: Fix Released

** Affects: ntp (Ubuntu)
     Importance: High
         Status: Fix Released

** Affects: ntp (Ubuntu Xenial)
     Importance: High
     Assignee: ChristianEhrhardt (paelzer)
         Status: Fix Committed

** Tags: apport-collected xenial
-- 
ntpd crashed with SIGABRT (was: ntp crashes everytime the network goes up or down.)
https://bugs.launchpad.net/bugs/1567540
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