| 2019-09-03 14:21:46 |
Mauricio Faria de Oliveira |
bug |
|
|
added bug |
| 2019-09-03 14:21:59 |
Mauricio Faria de Oliveira |
nominated for series |
|
Ubuntu Xenial |
|
| 2019-09-03 14:21:59 |
Mauricio Faria de Oliveira |
bug task added |
|
util-linux (Ubuntu Xenial) |
|
| 2019-09-03 14:22:06 |
Mauricio Faria de Oliveira |
util-linux (Ubuntu): status |
New |
Fix Released |
|
| 2019-09-03 14:22:12 |
Mauricio Faria de Oliveira |
util-linux (Ubuntu Xenial): status |
New |
In Progress |
|
| 2019-09-03 14:22:16 |
Mauricio Faria de Oliveira |
util-linux (Ubuntu Xenial): assignee |
|
Mauricio Faria de Oliveira (mfo) |
|
| 2019-09-03 14:22:22 |
Mauricio Faria de Oliveira |
util-linux (Ubuntu Xenial): importance |
Undecided |
Medium |
|
| 2019-09-03 16:59:35 |
Guilherme G. Piccoli |
bug |
|
|
added subscriber Guilherme G. Piccoli |
| 2019-09-05 22:44:27 |
Mauricio Faria de Oliveira |
description |
The nilfs filesystem has a backup superblock at the end of the device.
If the magic number is coincidentally found at the right position
and the filesystem is on a partition/not-wholedisk device,
the only check left is for checksum verification,
which is explicitly ignored in 'udev built-in blkid'.
This causes blkid to detect one actually valid filesystem with a
superblock at the beginning of the device (e.g., ext4), and then
an invalid nilfs2 filesystem due to a coincidental magic number
at the end of the device.
And this causes blkid to break out of the safeprobe routine
(which expects a single filesystem to be detected), and not
print the UUIDs, thus not creating /dev/disk/by-uuid/ links
which prevent mounting the partition by-uuid at boot time,
causing emergency shell/boot failures.
This upstream fix resolved the problem by introducing a check
for the 'bytes' paramenters in the superblock, which is read
from disk, and turns out to have an out-of-range value.
- 'liblkid: Add length check in probe_nilfs2 before crc32'
https://git.kernel.org/pub/scm/utils/util-linux/util-linux.git/commit/?id=ac681a310c32319423297544833932f4d689a7a2
$ git describe --contains ac681a310c32319423297544833932f4d689a7a2
v2.29-rc1~172
Xenial, which is v2.27.1-based, is the only release that needs it.
Bionic is v2.31.1, so all post-Xenial supported releases have it. |
[Impact]
* Users / systemd can fail to mount a filesystem by UUID
(e.g., during boot, triggering emergency shell prompt)
if the magic bytes for the nilfs filesystem are written
to the right place in a partition of another filesystem,
(for whatever reason or coincidence).
* Note this can happen after the filesystem/mount is working
correctly, so a change of behavior/problem can potentially
be noticed when trying to mount the filesystem again, which
can very well be the next time the system boots.
* This happens because if udev blkid detects more than one
filesystem, it does not print the UUID env vars required
to create the /dev/disk/by-id symlinks and other things.
* The fix enhances the check for valid nilfs superblock by
specifically checking a value read from disk to be valid/
within a value range, which addresses this one occurrence
and prevents a lot more.
[Test Case]
* Synthetic test case written for this problem on comment #6.
[Regression Potential]
* Low. The code is contained in the probe for the nilfs filesystem.
* This just makes it be more restrictive about the possibly valid
values for a few bytes read from disk (that now need to be within
the acceptable range of valid values) so this only decreases false-
positives, and cannot increase false-negatives of valid filesystems.
[Original Description]
The nilfs filesystem has a backup superblock at the end of the device.
If the magic number is coincidentally found at the right position
and the filesystem is on a partition/not-wholedisk device,
the only check left is for checksum verification,
which is explicitly ignored in 'udev built-in blkid'.
This causes blkid to detect one actually valid filesystem with a
superblock at the beginning of the device (e.g., ext4), and then
an invalid nilfs2 filesystem due to a coincidental magic number
at the end of the device.
And this causes blkid to break out of the safeprobe routine
(which expects a single filesystem to be detected), and not
print the UUIDs, thus not creating /dev/disk/by-uuid/ links
which prevent mounting the partition by-uuid at boot time,
causing emergency shell/boot failures.
This upstream fix resolved the problem by introducing a check
for the 'bytes' paramenters in the superblock, which is read
from disk, and turns out to have an out-of-range value.
- 'liblkid: Add length check in probe_nilfs2 before crc32'
https://git.kernel.org/pub/scm/utils/util-linux/util-linux.git/commit/?id=ac681a310c32319423297544833932f4d689a7a2
$ git describe --contains ac681a310c32319423297544833932f4d689a7a2
v2.29-rc1~172
Xenial, which is v2.27.1-based, is the only release that needs it.
Bionic is v2.31.1, so all post-Xenial supported releases have it. |
|
| 2019-09-05 22:48:11 |
Mauricio Faria de Oliveira |
attachment added |
|
lp1842437_util-linux.debdiff https://bugs.launchpad.net/ubuntu/+source/util-linux/+bug/1842437/+attachment/5287043/+files/lp1842437_util-linux.debdiff |
|
| 2019-09-05 22:48:38 |
Mauricio Faria de Oliveira |
util-linux (Ubuntu Xenial): assignee |
Mauricio Faria de Oliveira (mfo) |
Guilherme G. Piccoli (gpiccoli) |
|
| 2019-09-17 14:49:51 |
Mauricio Faria de Oliveira |
util-linux (Ubuntu Xenial): assignee |
Guilherme G. Piccoli (gpiccoli) |
Mauricio Faria de Oliveira (mfo) |
|
| 2019-09-17 14:53:30 |
Mauricio Faria de Oliveira |
bug |
|
|
added subscriber STS Sponsors |
| 2019-09-17 14:57:12 |
Mauricio Faria de Oliveira |
tags |
|
sts |
|
| 2019-09-17 15:01:07 |
Eric Desrochers |
tags |
sts |
sts sts-sponsor-slashd |
|
| 2019-09-17 15:02:40 |
Dan Streetman |
bug |
|
|
added subscriber Dan Streetman |
| 2019-09-17 16:30:11 |
Eric Desrochers |
bug |
|
|
added subscriber Eric Desrochers |
| 2019-09-24 11:47:05 |
Eric Desrochers |
tags |
sts sts-sponsor-slashd |
ftbfs sts sts-sponsor-slashd |
|
| 2019-10-04 15:01:57 |
Eric Desrochers |
removed subscriber STS Sponsors |
|
|
|
| 2019-10-10 09:29:34 |
Łukasz Zemczak |
util-linux (Ubuntu Xenial): status |
In Progress |
Fix Committed |
|
| 2019-10-10 09:29:37 |
Łukasz Zemczak |
bug |
|
|
added subscriber Ubuntu Stable Release Updates Team |
| 2019-10-10 09:29:38 |
Łukasz Zemczak |
bug |
|
|
added subscriber SRU Verification |
| 2019-10-10 19:40:44 |
Mauricio Faria de Oliveira |
tags |
ftbfs sts sts-sponsor-slashd |
ftbfs sts sts-sponsor-slashd verification-done-xenial |
|
| 2019-10-15 11:32:24 |
Eric Desrochers |
tags |
ftbfs sts sts-sponsor-slashd verification-done-xenial |
ftbfs sts verification-done-xenial |
|
| 2019-10-21 14:52:04 |
Łukasz Zemczak |
removed subscriber Ubuntu Stable Release Updates Team |
|
|
|
| 2019-10-21 15:02:10 |
Launchpad Janitor |
util-linux (Ubuntu Xenial): status |
Fix Committed |
Fix Released |
|
