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serial: 8250_of: clear stuck empty-FIFO RX-timeout on LPC32xx

Type: advisorySource: Official CVE List1 source record

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 (

Announced Source revision 1
Original source ↗

CVE-2026-74653

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-74653

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
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Prerequisites
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Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "e6e912c4964ce5976e508881207dfa96d5f856d7",
        "lessThan": "cc325ce1c40a111824827532ac132afb3d1c342b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "e6e912c4964ce5976e508881207dfa96d5f856d7",
        "lessThan": "c321dc5172c8c66e21ffbeeb7a2ebb88ae6fd4c3",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "e6e912c4964ce5976e508881207dfa96d5f856d7",
        "lessThan": "3ce24bc4d115336218e59b7e286fd3a79f4fc4c6",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "e6e912c4964ce5976e508881207dfa96d5f856d7",
        "lessThan": "7795e8abedc86438cae0454602cbf9038b94bf38",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "e6e912c4964ce5976e508881207dfa96d5f856d7",
        "lessThan": "1423415471274abda87024967d7fe2206ceee0ea",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "drivers/tty/serial/8250/8250_of.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "2.6.36"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "2.6.36",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.106",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.45",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.1.9",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "drivers/tty/serial/8250/8250_of.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-74653

Source reference: /cveMetadata/cveId

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Event
#46584 · Revision 1
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