Bug 172334 - unionfs permits recursive union mounts; causes panic quickly
Summary: unionfs permits recursive union mounts; causes panic quickly
Status: Open
Alias: None
Product: Base System
Classification: Unclassified
Component: kern (show other bugs)
Version: 9.0-RELEASE
Hardware: Any Any
: Normal Affects Only Me
Assignee: Jason A. Harmening
URL:
Keywords: crash
Depends on:
Blocks:
 
Reported: 2012-10-04 20:00 UTC by Enji Cooper
Modified: 2024-02-04 01:01 UTC (History)
4 users (show)

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Description Enji Cooper freebsd_committer freebsd_triage 2012-10-04 20:00:21 UTC 
I accidentally got my invocation backwards, was impatient and tried the opposite form and it blew up looking in the VOP code when I did the following:

1. Boot 9.0-RELEASE as a LiveCD.
2. Execute the following commands:
   mkdir /tmp/etc
   mount_unionfs /tmp/etc /etc
   mount_unionfs /etc /tmp/etc
3. Accessing either /etc or /tmp/etc after that should result in a panic.
Comment 1 Mark Linimon freebsd_committer freebsd_triage 2012-10-05 03:14:13 UTC 
Responsible Changed
From-To: freebsd-bugs->freebsd-fs

Over to maintainer(s).
Comment 2 daichi 2012-10-18 09:17:59 UTC 
You could around this issue with a following patch.

  http://people.freebsd.org/~daichi/unionfs/unionfs-cross-mount3.diff

And above patch is rejected at ml discussion some years ago. 
We need more radical changes to improve this kind of issues.

--
Daichi GOTO
81-42-316-7945 | daichi@ongs.co.jp | http://www.ongs.co.jp
LinkedIn: http://linkedin.com/in/daichigoto
Comment 3 Enji Cooper freebsd_committer freebsd_triage 2013-06-12 01:10:20 UTC 
I finally got around to testing this. Yup -- the patch looks good to me.
Thank you Daichi!
-Garrett
Comment 4 Brad Davis freebsd_committer freebsd_triage 2015-07-30 21:41:30 UTC 
ping
Comment 5 Eitan Adler freebsd_committer freebsd_triage 2018-05-28 19:47:31 UTC 
batch change:

For bugs that match the following
-  Status Is In progress 
AND
- Untouched since 2018-01-01.
AND
- Affects Base System OR Documentation

DO:

Reset to open status.


Note:
I did a quick pass but if you are getting this email it might be worthwhile to double check to see if this bug ought to be closed.
Comment 6 Jason A. Harmening freebsd_committer freebsd_triage 2024-02-04 00:58:59 UTC 
See comments 9 & 10 on https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=275871 for a more recent reproduction.