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Unity Linux 20.1050e Security Update: kernel (UTSA-2026-006756)
medium Nessus Plugin ID 305551
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-2026-006756 advisory.In the Linux kernel, the following vulnerability has been resolved:
cifs: Release folio lock on fscache read hit.
Under the current code, when cifs_readpage_worker is called, the call contract is that the callee should unlock the page. This is documented in the read_folio section of Documentation/filesystems/vfs.rst as:
> The filesystem should unlock the folio once the read has completed, > whether it was successful or not.
Without this change, when fscache is in use and cache hit occurs during a read, the page lock is leaked, producing the following stack on subsequent reads (via mmap) to the page:
$ cat /proc/3890/task/12864/stack [<0>] folio_wait_bit_common+0x124/0x350 [<0>] filemap_read_folio+0xad/0xf0 [<0>] filemap_fault+0x8b1/0xab0 [<0>] __do_fault+0x39/0x150 [<0>] do_fault+0x25c/0x3e0 [<0>] __handle_mm_fault+0x6ca/0xc70 [<0>] handle_mm_fault+0xe9/0x350 [<0>] do_user_addr_fault+0x225/0x6c0 [<0>] exc_page_fault+0x84/0x1b0 [<0>] asm_exc_page_fault+0x27/0x30
This requires a reboot to resolve; it is a deadlock.
Note however that the call to cifs_readpage_from_fscache does mark the page clean, but does not free the folio lock. This happens in
__cifs_readpage_from_fscache on success. Releasing the lock at that point however is not appropriate as cifs_readahead also calls cifs_readpage_from_fscache and *does* unconditionally release the lock after its return. This change therefore effectively makes cifs_readpage_worker work like cifs_readahead.
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?caf643e6
Plugin Details
Severity: Medium
ID: 305551
File Name: unity_linux_UTSA-2026-006756.nasl
Version: 1.1
Type: Local
Published: 4/8/2026
Updated: 4/8/2026
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-2023-53593
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/cpu, Host/UOS-Server/release, Host/UOS-Server/rpm-list
Exploit Ease: No known exploits are available
Patch Publication Date: 4/8/2026
Vulnerability Publication Date: 7/21/2021
Reference Information
CVE: CVE-2023-53593