Potential data loss in CryFS 0.9.9 (fixed in 0.9.10)
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
cryfs (Ubuntu) |
Fix Released
|
Medium
|
Unassigned | ||
Bionic |
Confirmed
|
Medium
|
Unassigned |
Bug Description
CryFS 0.9.10 fixed a dead lock and a race condition, the latter of which can cause data loss if the file system is under heavy load and accessed concurrently.
Changelog: https:/
Some user reports about the data loss:
- https:/
- https:/
- https:/
This issue is fixed in 0.9.10 but stable Ubuntu versions (bionic, cosmic) still distribute 0.9.9.
The package should be updated in the software repositories.
Versioning notes:
- 0.9.10 is a new upstream microrelease.
- A 0.9.10 package is already in Debian and Ubuntu Disco, see https:/
- Debian will soon update to 0.10, and Ubuntu Disco is expected to follow. However, older Ubuntu versions should not update to 0.10.0 but only to 0.9.10 to fix the data loss bug.
[Test Case]
Follow the instructions in the linked GitHub issues. Since this is a race condition, it doesn't always manifest, but https:/
1. Create a file system using CryFS 0.9.9
$ cryfs -f /tmp/basedir /tmp/mountdir
Note: the '-f' causes CryFS to run in foreground, i.e. you won't get your terminal back. Keep it running and open a new terminal for the next commands.
2. Create a video file in the mounted directory
$ ffmpeg -i some_video_file.mp4 /tmp/mountdir/
3. Open /tmp/mountdir/
$ vlc /tmp/mountdir/
4. While it is running, re-create it
$ ffmpeg -i some_video_file.mp4 /tmp/mountdir/
5. Observe the crash in the terminal running the CryFS process
6. Try the same with CryFS 0.9.10 and observe that it doesn't crash.
[Regression Potential]
The race condition was fixed in 0.9.10 using additional mutexes, so the most likely regression is the introduction of a new deadlock.
Generally, CryFS has a very extensive test suite and CI that is run on each commit and each release, see https:/
This test suite is also run automatically when the Debian package is created.
description: | updated |
description: | updated |
description: | updated |
Changed in cryfs (Ubuntu): | |
status: | New → Fix Released |
importance: | Undecided → Medium |
Changed in cryfs (Ubuntu Bionic): | |
importance: | Undecided → Medium |
tags: | added: bionic cosmic |
Changed in cryfs (Ubuntu Bionic): | |
status: | In Progress → Confirmed |
assignee: | Simon Quigley (tsimonq2) → nobody |
Hello Sebastian, thanks for your work on this! I appreciate the thorough and standards-compliant bug description on the first try. :)
I no-change backported 0.9.10-1 to Bionic and uploaded it to the queue. I didn't backport 0.9.10-2 because it is a mipsel-related change that really isn't appropriate for an SRU. 0.9.9-2 is equivalent to 0.9.9-1ubuntu1, so it can replace that change.
Unsubscribing the Ubuntu Sponsors Team.