[Bug 1883025] Re: [focal SRU] davfs2 unable to unmount: segfault error 4 in libc.so

Mathew Hodson 1883025 at bugs.launchpad.net
Tue Apr 6 04:59:45 UTC 2021

Fixed in Ubuntu Groovy and later.

davfs2 (1.5.6-0.1) unstable; urgency=medium

  * Non-maintainer upload.
  * New upstream version.
  * Standards-Version: 4.5.0
  * Fix incompatible neon library version by adding 31 to configure.ac.
  * Fix a lintian warning of debian-watch-uses-insecure-uri.

 -- Hsieh-Tseng Shen <woodrow.shen at gmail.com>  Thu, 18 Jun 2020 13:58:12

** Also affects: davfs2 (Ubuntu Focal)
   Importance: Undecided
       Status: New

** Changed in: davfs2 (Ubuntu)
   Importance: Undecided => Medium

** Changed in: davfs2 (Ubuntu Focal)
   Importance: Undecided => Medium

** Changed in: davfs2 (Ubuntu)
       Status: In Progress => Fix Released

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  [focal SRU] davfs2 unable to unmount: segfault error 4 in libc.so

Status in davfs2 package in Ubuntu:
  Fix Released
Status in davfs2 source package in Focal:

Bug description:

  umount.davfs consistently segfault in focal.  This leads to a number
  of medium severity issues.

  - inability to unmount (this might have security implications)
  - inability to remount
  - autofs fails to unmount
  - reports of higher load in multi-user environments
  - computer "hangs" on shutdown waiting for successful umount completion


  No need for a specific test case, simply mount a resource via
  davfs2.mount.  Calling umount.davfs2 on that mount in focal will
  result in a segfault every time.  Exit code 255 and failure is
  recorded in syslog.  The mount stays mounted.

  To verify the fix from #2 which is the backport of the fix from
  upstream, simply recompile davfs2 and try the procedure once more to
  see if the problem has been solved.


  I will leave this mostly to others to evaluate.  Currently,
  umount.davfs2 is completely dysfunctional so it's hard to imagine a
  regression for a binary that isn't doing anything except segfaulting.

  [racb] Code that parses its own pidfile is being fixed. It was
  segfaulting before, so as mentioned it is unlikely to break further as
  a cause of this patch, except the normal latent bug being exposed on
  rebuild risk. If there is a problem with the pidfile parsing being
  introduced, then code further down this path could break.


  groovy and later versions have already been fixed via a new upstream
  release.  Upstream discussion of the a and m mixup can be found at the
  links below.  Duplicate bug 1859293 also has some very good


  I am getting segfaults everytime I want to unmount my webdav online-
  space (segfault error 4).

  Hardware failure is impossible as I see - because error already reported on project page (and fixed).
  Error should be fixed in davfs 1.5.6 (Maybe easiest to bump to version 1.5.6 on ubuntu repos ?) :)

  See (line 4-6):

  See 2:

  EDIT: Using Ubuntu 20.04 x64

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