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Unity Linux 20.1070e Security Update: kernel (UTSA-2026-010820)
medium Nessus Plugin ID 308820
Synopsis
The Unity Linux host is missing one or more security updates.Description
The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the UTSA-2026-010820 advisory.In the Linux kernel, the following vulnerability has been resolved:
dm cache: prevent BUG_ON by blocking retries on failed device resumes
A cache device failing to resume due to mapping errors should not be retried, as the failure leaves a partially initialized policy object.
Repeating the resume operation risks triggering BUG_ON when reloading cache mappings into the incomplete policy object.
Reproduce steps:
1. create a cache metadata consisting of 512 or more cache blocks, with some mappings stored in the first array block of the mapping array. Here we use cache_restore v1.0 to build the metadata.
cat <<EOF >> cmeta.xml <superblock uuid= block_size=128 nr_cache_blocks=512 \ policy=smq hint_width=4> <mappings> <mapping cache_block=0 origin_block=0 dirty=false/> </mappings> </superblock> EOF dmsetup create cmeta --table 0 8192 linear /dev/sdc 0 cache_restore -i cmeta.xml -o /dev/mapper/cmeta --metadata-version=2 dmsetup remove cmeta
2. wipe the second array block of the mapping array to simulate data degradations.
mapping_root=$(dd if=/dev/sdc bs=1c count=8 skip=192 \ 2>/dev/null | hexdump -e '1/8 %u\n') ablock=$(dd if=/dev/sdc bs=1c count=8 skip=$((4096*mapping_root+2056)) \ 2>/dev/null | hexdump -e '1/8 %u\n') dd if=/dev/zero of=/dev/sdc bs=4k count=1 seek=$ablock
3. try bringing up the cache device. The resume is expected to fail due to the broken array block.
dmsetup create cmeta --table 0 8192 linear /dev/sdc 0 dmsetup create cdata --table 0 65536 linear /dev/sdc 8192 dmsetup create corig --table 0 524288 linear /dev/sdc 262144 dmsetup create cache --notable dmsetup load cache --table 0 524288 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0 dmsetup resume cache
4. try resuming the cache again. An unexpected BUG_ON is triggered while loading cache mappings.
dmsetup resume cache
Kernel logs:
(snip)
------------[ cut here ]------------ kernel BUG at drivers/md/dm-cache-policy-smq.c:752! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 0 UID: 0 PID: 332 Comm: dmsetup Not tainted 6.13.4 #3 RIP: 0010:smq_load_mapping+0x3e5/0x570
Fix by disallowing resume operations for devices that failed the initial attempt.
Tenable has extracted the preceding description block directly from the Unity Linux security advisory.
Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.
Solution
Update the affected kernel package.See Also
http://www.nessus.org/u?691a4063
Plugin Details
Severity: Medium
ID: 308820
File Name: unity_linux_UTSA-2026-010820.nasl
Version: 1.1
Type: Local
Published: 4/21/2026
Updated: 4/21/2026
Supported Sensors: Nessus
Risk Information
VPR
Risk Factor: Medium
Score: 4.4
CVSS v2
Risk Factor: Medium
Base Score: 4.6
Temporal Score: 3.4
Vector: CVSS2#AV:L/AC:L/Au:S/C:N/I:N/A:C
CVSS Score Source: CVE-2025-38066
CVSS v3
Risk Factor: Medium
Base Score: 5.5
Temporal Score: 4.8
Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C
Vulnerability Information
Required KB Items: Host/local_checks_enabled, Host/UOS-Server/release, Host/UOS-Server/rpm-list, Host/cpu
Exploit Ease: No known exploits are available
Patch Publication Date: 4/20/2026
Vulnerability Publication Date: 6/11/2025
Reference Information
CVE: CVE-2025-38066