CVE-2025-39724
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: serial: 8250: fix panic due to PSLVERR When the PSLVERR_RESP_EN parameter is set to 1, the device generates an error response if an attempt is made to read an empty RBR (Receive Buffer Register) while the FIFO is enabled. In serial8250_do_startup(), calling serial_port_out(port, UART_LCR, UART_LCR_WLEN8) triggers dw8250_check_lcr(), which invokes dw8250_force_idle() and serial8250_clear_and_reinit_fifos(). The latter function enables the FIFO via serial_out(p, UART_FCR, p->fcr). Execution proceeds to the serial_port_in(port, UART_RX). This satisfies the PSLVERR trigger condition. When another CPU (e.g., using printk()) is accessing the UART (UART is busy), the current CPU fails the check (value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR) in dw8250_check_lcr(), causing it to enter dw8250_force_idle(). Put serial_port_out(port, UART_LCR, UART_LCR_WLEN8) under the port->lock to fix this issue. Panic backtrace: [ 0.442336] Oops - unknown exception [#1] [ 0.442343] epc : dw8250_serial_in32+0x1e/0x4a [ 0.442351] ra : serial8250_do_startup+0x2c8/0x88e ... [ 0.442416] console_on_rootfs+0x26/0x70
Severity
MEDIUM
CVSS score
5.5
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-09-05 18:15:50.177000
Last modified
2026-10-19 21:10:00.160000
View original CVE JSON
{
"id": "CVE-2025-39724",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2025-09-05T18:15:50.177",
"lastModified": "2026-10-19T21:10:00.160",
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{
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nserial: 8250: fix panic due to PSLVERR\n\nWhen the PSLVERR_RESP_EN parameter is set to 1, the device generates\nan error response if an attempt is made to read an empty RBR (Receive\nBuffer Register) while the FIFO is enabled.\n\nIn serial8250_do_startup(), calling serial_port_out(port, UART_LCR,\nUART_LCR_WLEN8) triggers dw8250_check_lcr(), which invokes\ndw8250_force_idle() and serial8250_clear_and_reinit_fifos(). The latter\nfunction enables the FIFO via serial_out(p, UART_FCR, p->fcr).\nExecution proceeds to the serial_port_in(port, UART_RX).\nThis satisfies the PSLVERR trigger condition.\n\nWhen another CPU (e.g., using printk()) is accessing the UART (UART\nis busy), the current CPU fails the check (value & ~UART_LCR_SPAR) ==\n(lcr & ~UART_LCR_SPAR) in dw8250_check_lcr(), causing it to enter\ndw8250_force_idle().\n\nPut serial_port_out(port, UART_LCR, UART_LCR_WLEN8) under the port->lock\nto fix this issue.\n\nPanic backtrace:\n[ 0.442336] Oops - unknown exception [#1]\n[ 0.442343] epc : dw8250_serial_in32+0x1e/0x4a\n[ 0.442351] ra : serial8250_do_startup+0x2c8/0x88e\n...\n[ 0.442416] console_on_rootfs+0x26/0x70"
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{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nserial: 8250: corrección de pánico debido a PSLVERR\n\nCuando el parámetro PSLVERR_RESP_EN se establece en 1, el dispositivo genera una respuesta de error si se intenta leer un RBR (Receive Buffer Register) vacío mientras el FIFO está habilitado.\n\nEn serial8250_do_startup(), la llamada a serial_port_out(port, UART_LCR, UART_LCR_WLEN8) activa dw8250_check_lcr(), que invoca dw8250_force_idle() y serial8250_clear_and_reinit_fifos(). Esta última función habilita el FIFO a través de serial_out(p, UART_FCR, p->fcr). La ejecución continúa hasta el serial_port_in(port, UART_RX). Esto satisface la condición de activación de PSLVERR.\n\nCuando otra CPU (por ejemplo, usando printk()) está accediendo a la UART (la UART está ocupada), la CPU actual falla la verificación (value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR) en dw8250_check_lcr(), lo que hace que entre en dw8250_force_idle().\n\nColocar serial_port_out(port, UART_LCR, UART_LCR_WLEN8) bajo el port->lock para solucionar este problema.\n\nRastreo de pánico:\n[ 0.442336] Oops - excepción desconocida [#1]\n[ 0.442343] epc : dw8250_serial_in32+0x1e/0x4a\n[ 0.442351] ra : serial8250_do_startup+0x2c8/0x88e\n...\n[ 0.442416] console_on_rootfs+0x26/0x70"
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