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

Rolf Leggewie 1883025 at bugs.launchpad.net
Sun Apr 4 14:17:42 UTC 2021


I can confirm that the debdiff from #2 fixes the issue.  Thank you.

I will upload a bugfixed package to my LTS PPA
https://launchpad.net/~r0lf/+archive/ubuntu/stable

** Description changed:

  [IMPACT]
  
  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
  
  [TEST CASE]
  
  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.
  
  [REGRESSION POTENTIAL]
  
  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.
  
  [OTHER INFO]
  
  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.
- 
+ links below.  Duplicate bug 1859293 also has some very good background.
  
  [ORIGINAL REPORT]
  
  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):
  http://cvs.savannah.nongnu.org/viewvc/davfs2/davfs2/ChangeLog?revision=1.156&view=markup&pathrev=MAIN
  
  See 2:
  https://savannah.nongnu.org/bugs/?func=detailitem&item_id=56286#options
  
  EDIT: Using Ubuntu 20.04 x64

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https://bugs.launchpad.net/bugs/1883025

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

Status in davfs2 package in Ubuntu:
  Confirmed

Bug description:
  [IMPACT]

  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

  [TEST CASE]

  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.

  [REGRESSION POTENTIAL]

  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.

  [OTHER INFO]

  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
  background.

  [ORIGINAL REPORT]

  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):
  http://cvs.savannah.nongnu.org/viewvc/davfs2/davfs2/ChangeLog?revision=1.156&view=markup&pathrev=MAIN

  See 2:
  https://savannah.nongnu.org/bugs/?func=detailitem&item_id=56286#options

  EDIT: Using Ubuntu 20.04 x64

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