{"apiVersion":"1.0","identifier":"CVE-2026-74653","description":"In the Linux kernel, the following vulnerability has been resolved: serial: 8250_of: clear stuck empty-FIFO RX-timeout on LPC32xx The NXP LPC32xx UART (PORT_LPC3220) can latch an RX character-timeout interrupt while the RX FIFO is empty: IIR reports UART_IIR_RX_TIMEOUT (0x0c) but LSR.DR is clear. A character timeout is only cleared by reading RHR, but serial8250_rx_chars() reads RHR only when LSR.DR is set, so nothing ever clears the condition. The interrupt is level-triggered and re-fires immediately, so on a single-core ARM926 the resulting interrupt storm livelocks the CPU. It is reproducible when userspace repeatedly opens the front-panel port (ttyS1): serial8250_do_set_termios() re-enables interrupts on unlock and the handler then spins forever with iir=0xcc lsr=0x60 ier=0x05, tripping the soft-lockup detector in serial8250_handle_irq_locked(). LPC32xx has no dedicated 8250 glue driver, it-s driven by the generic 8250_of. Add a hardware specific handle_irq for PORT_LPC3220, wired up in of_platform_serial_setup() the same way fsl8250_handle_irq is installed. The handler follows dw8250_handle_irq(): on an RX timeout with an empty FIFO (LSR.DR and LSR.BI clear) it does one throwaway RHR read to clear the condition, then calls serial8250_handle_irq_locked(). No real received data is ever discarded, and it is a no-op on healthy UARTs which never report a timeout with DR clear. This is the same class of bug already worked around in other 8250 drivers; see commit 424d79183af0 (-serial: 8250_dw: Avoid -too much work- from bogus rx timeout interrupt-) which reports the identical iir=0xcc/lsr=0x60. See also UART_RX_TIMEOUT_QUIRK in 8250_omap, and the note in 8250_bcm7271.","publishedAt":"2026-08-22T16:16:38","lastModifiedAt":"2026-08-27T13:18:35","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-74653","cvssScore":null,"cvssVector":"Pending","epssProbability":0.00168,"riskScore":0,"affectedProduct":"Linux kernel","affectedVersions":"unknown","vulnerabilityType":"Kernel","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-74653","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-74653","en":"https://www.redsauce.net/en/cves/CVE-2026-74653","fr":"https://www.redsauce.net/fr/cves/CVE-2026-74653","pt":"https://www.redsauce.net/pt/cves/CVE-2026-74653","de":"https://www.redsauce.net/de/cves/CVE-2026-74653","sk":"https://www.redsauce.net/sk/cves/CVE-2026-74653","el":"https://www.redsauce.net/el/cves/CVE-2026-74653"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-74653"}}