CVE-2025-39724

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

PUBLISHED Reserved 2025-04-16 | Published 2025-09-05 | Updated 2025-09-29 | Assigner Linux

Product status

References

git.kernel.org/...c/0b882f00655afefbc7729c6b5aec86f7a5473a3d

git.kernel.org/...c/b8ca8e3f75ede308b4d49a6ca5081460be01bdb5

git.kernel.org/...c/68c4613e89f000e8198f9ace643082c697921c9f

git.kernel.org/...c/c826943abf473a3f7260fbadfad65e44db475460

git.kernel.org/...c/cb7b3633ed749db8e56f475f43c960652cbd6882

git.kernel.org/...c/8e2739478c164147d0774802008528d9e03fb802

git.kernel.org/...c/38c0ea484dedb58cb3a4391229933e16be0d1031

git.kernel.org/...c/7f8fdd4dbffc05982b96caf586f77a014b2a9353

cve.org (CVE-2025-39724)

nvd.nist.gov (CVE-2025-39724)

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