Arch Linux

Description:
the current blkid in util-linux-2.24 can now recognize the extend
partition, but os-prober relies on the return value "2" (exit_not_found)
of blkid to skip processing the extend partition.

so, os-prober will try to mount the extend partition with FS types
found in the system, which is dangerous.

# fdisk -l
....
Device Boot Start End Blocks Id System
/dev/sda1 * 63 252847034 126423486 7 HPFS/NTFS/exFAT
/dev/sda2 252847035 625137344 186145155 5 Extended
/dev/sda5 252847098 253425374 289138+ 83 Linux
/dev/sda6 385254828 482913899 48829536 83 Linux
....


blkid 2.24-2
---
# blkid /dev/sda2
/dev/sda2: PTTYPE="dos" PARTUUID="28b48ca1-02"
# echo $?
0

# blkid -o value -s TYPE /dev/sda2 # no output
# echo $?
0


blkid 2.20.0
---
# blkid /dev/sda2 # no output
# echo $?
2
# blkid -o value -s TYPE /dev/sda2 # no output
# echo $?
2


Affected os-prober code:
---
File: /usr/lib/os-probes/50mounted-tests
-
8 types="$(fs_type "$partition")" || types=NOT-DETECTED
9 if [ "$types" = NOT-DETECTED ]; then
10 debug "$1 type not recognised; skipping"
11 exit 0


With the old blkid (util-linux-2.20),
os-prober will just skip here when handling /dev/sda2,
but with the new version of blkid,
os-prober will go on and try to mount /dev/sda2 with
FS types found in the system, which causes lots of errors,
even kernel calltrace when trying xfs.


Additional info:
* os-prober 1.58-1
* util-linux 2.24-2


Steps to reproduce:
1. run os-prober
# os-prober

2. check the log
# journalctl
with util-linux-2.20, the log is like:
--
50mounted-tests: debug: /dev/sda2 type not recognised; skipping
--
but with util-linux-2.24, os-prober will try various FS types to
mount /dev/sda2

3. check dmesg
as xfs exists in the system, a kernel calltrace will show,
xfs tool would try to "fix" the "data corruption".