CVE-2025-21820

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  2. Vulnerabilities (CVE)
  3. CVE-2025-21820

5.5 /10

CVSS v3 : MEDIUM

V3 Legend

Vector :

Exploitability : 1.8 / Impact : 3.6

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

I

n the Linux kernel, the following vulnerability has been resolved: tty: xilinx_uartps: split sysrq handling lockdep detects the following circular locking dependency: CPU 0 CPU 1 ========================== ============================ cdns_uart_isr() printk() uart_port_lock(port) console_lock() cdns_uart_console_write() if (!port->sysrq) uart_port_lock(port) uart_handle_break() port->sysrq = ... uart_handle_sysrq_char() printk() console_lock() The fixed commit attempts to avoid this situation by only taking the port lock in cdns_uart_console_write if port->sysrq unset. However, if (as shown above) cdns_uart_console_write runs before port->sysrq is set, then it will try to take the port lock anyway. This may result in a deadlock. Fix this by splitting sysrq handling into two parts. We use the prepare helper under the port lock and defer handling until we release the lock.

References
Link Resource
https://git.kernel.org/stable/c/4410dba9807a17a93f649a9f5870ceaf30a675a3 Patch
https://git.kernel.org/stable/c/8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801c Patch
https://git.kernel.org/stable/c/9b88a7c4584ba67267a051069b8abe44fc9595b2 Patch
https://git.kernel.org/stable/c/b06f388994500297bb91be60ffaf6825ecfd2afe Patch
https://git.kernel.org/stable/c/de5bd24197bd9ee37ec1e379a3d882bbd15c5065 Patch
https://git.kernel.org/stable/c/e22a97700901ba5e8bf8db68056a0d50f9440cae
https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
Configurations

Configuration 1 (hide)

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
History

03 Nov 2025, 21:19

Type Values Removed Values Added
References
  • () https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html -

13 Mar 2025, 13:15

Type Values Removed Values Added
CVSS v2 : unknown
v3 : unknown 		v2 : unknown
v3 : 5.5
CWE CWE-667
References
  • () https://git.kernel.org/stable/c/e22a97700901ba5e8bf8db68056a0d50f9440cae -
References () https://git.kernel.org/stable/c/4410dba9807a17a93f649a9f5870ceaf30a675a3 - () https://git.kernel.org/stable/c/4410dba9807a17a93f649a9f5870ceaf30a675a3 - Patch
References () https://git.kernel.org/stable/c/8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801c - () https://git.kernel.org/stable/c/8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801c - Patch
References () https://git.kernel.org/stable/c/9b88a7c4584ba67267a051069b8abe44fc9595b2 - () https://git.kernel.org/stable/c/9b88a7c4584ba67267a051069b8abe44fc9595b2 - Patch
References () https://git.kernel.org/stable/c/b06f388994500297bb91be60ffaf6825ecfd2afe - () https://git.kernel.org/stable/c/b06f388994500297bb91be60ffaf6825ecfd2afe - Patch
References () https://git.kernel.org/stable/c/de5bd24197bd9ee37ec1e379a3d882bbd15c5065 - () https://git.kernel.org/stable/c/de5bd24197bd9ee37ec1e379a3d882bbd15c5065 - Patch
First Time Linux
Linux linux Kernel
Summary
  • (es) En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: tty: xilinx_uartps: la gestión dividido de sysrq lockdep detecta la siguiente dependencia de bloqueo circular: CPU 0 CPU 1 ========================== ============================ cdns_uart_isr() printk() uart_port_lock(port) console_lock() cdns_uart_console_write() if (!port->sysrq) uart_port_lock(port) uart_handle_break() port->sysrq = ... uart_handle_sysrq_char() printk() console_lock() The fixed commit attempts to avoid this situation by only taking the port lock in cdns_uart_console_write if port->sysrq unset. Sin embargo, si (como se muestra arriba) cdns_uart_console_write se ejecuta antes de que port->sysrq esté configurado, entonces intentará tomar el bloqueo del puerto de todos modos. Esto puede resultar en un bloqueo. Solucione esto dividiendo la gestión de sysrq en dos partes. Usamos el asistente de preparación bajo el bloqueo del puerto y posponemos la gestión hasta que liberemos el bloqueo.
CPE cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

27 Feb 2025, 20:16

Type Values Removed Values Added
New CVE
Information

Published : 2025-02-27 20:16

Updated : 2025-11-03 21:19

NVD link : CVE-2025-21820

Mitre link : CVE-2025-21820

CVE.ORG link : CVE-2025-21820

JSON object : View

Products Affected

linux

CWE
CWE-667

Improper Locking