// For flags

CVE-2021-47369

s390/qeth: fix NULL deref in qeth_clear_working_pool_list()

Severity Score

5.5
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track
*SSVC
Descriptions

In the Linux kernel, the following vulnerability has been resolved:

s390/qeth: fix NULL deref in qeth_clear_working_pool_list()

When qeth_set_online() calls qeth_clear_working_pool_list() to roll
back after an error exit from qeth_hardsetup_card(), we are at risk of
accessing card->qdio.in_q before it was allocated by
qeth_alloc_qdio_queues() via qeth_mpc_initialize().

qeth_clear_working_pool_list() then dereferences NULL, and by writing to
queue->bufs[i].pool_entry scribbles all over the CPU's lowcore.
Resulting in a crash when those lowcore areas are used next (eg. on
the next machine-check interrupt).

Such a scenario would typically happen when the device is first set
online and its queues aren't allocated yet. An early IO error or certain
misconfigs (eg. mismatched transport mode, bad portno) then cause us to
error out from qeth_hardsetup_card() with card->qdio.in_q still being
NULL.

Fix it by checking the pointer for NULL before accessing it.

Note that we also have (rare) paths inside qeth_mpc_initialize() where
a configuration change can cause us to free the existing queues,
expecting that subsequent code will allocate them again. If we then
error out before that re-allocation happens, the same bug occurs.

Root-caused-by: Heiko Carstens <hca@linux.ibm.com>

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: s390/qeth: corrige NULL deref en qeth_clear_working_pool_list(). Cuando qeth_set_online() llama a qeth_clear_working_pool_list() para retroceder después de una salida de error de qeth_hardsetup_card(), corremos el riesgo de acceder a la tarjeta -&gt;qdio.in_q antes de que qeth_alloc_qdio_queues() lo asignara mediante qeth_mpc_initialize(). qeth_clear_working_pool_list() luego elimina la referencia a NULL y, al escribir en queue-&gt;bufs[i].pool_entry garabatea por todo el núcleo bajo de la CPU. Lo que resulta en un bloqueo cuando esas áreas de núcleo bajo se usan a continuación (por ejemplo, en la siguiente interrupción de verificación de la máquina). Este escenario suele ocurrir cuando el dispositivo se configura en línea por primera vez y sus colas aún no están asignadas. Un error de IO temprano o ciertas configuraciones erróneas (por ejemplo, modo de transporte no coincidente, número de puerto incorrecto) hacen que salgamos del error qeth_hardsetup_card() con card-&gt;qdio.in_q todavía siendo NULL. Solucionarlo comprobando que el puntero sea NULL antes de acceder a él. Tenga en cuenta que también tenemos rutas (raras) dentro de qeth_mpc_initialize() donde un cambio de configuración puede hacer que liberemos las colas existentes, esperando que el código posterior las asigne nuevamente. Si luego cometemos un error antes de que ocurra la reasignación, ocurre el mismo error. Analizado por: Heiko Carstens

*Credits: N/A
CVSS Scores
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
* Common Vulnerability Scoring System
SSVC
  • Decision:Track
Exploitation
None
Automatable
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2024-05-21 CVE Reserved
  • 2024-05-21 CVE Published
  • 2024-05-22 EPSS Updated
  • 2024-12-19 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-476: NULL Pointer Dereference
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 5.9 < 5.10.70
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.9 < 5.10.70"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 5.9 < 5.14.9
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.9 < 5.14.9"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 5.9 < 5.15
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.9 < 5.15"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
5.7.16
Search vendor "Linux" for product "Linux Kernel" and version "5.7.16"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
5.8.2
Search vendor "Linux" for product "Linux Kernel" and version "5.8.2"
en
Affected