CVE-2025-21820

CVE-2025-21820

Título es
CVE-2025-21820

Jue, 27/02/2025 – 20:16

Gravedad 2.0 Txt
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Título en

CVE-2025-21820

Descripción en
In 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.

27/02/2025

27/02/2025

Gravedad 3.1 Txt Gravedad 3.1 (CVSS 3.1 Base Score)
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