Vulnerability-Lookup

GHSA-HPJX-F9R3-XJ76

Vulnerability from github – Published: 2026-08-22 18:30 – Updated: 2026-10-21 15:40

Details

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.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-74653"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-22T16:16:38Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nserial: 8250_of: clear stuck empty-FIFO RX-timeout on LPC32xx\n\nThe NXP LPC32xx UART (PORT_LPC3220) can latch an RX character-timeout\ninterrupt while the RX FIFO is empty: IIR reports UART_IIR_RX_TIMEOUT\n(0x0c) but LSR.DR is clear. A character timeout is only cleared by\nreading RHR, but serial8250_rx_chars() reads RHR only when LSR.DR is\nset, so nothing ever clears the condition. The interrupt is\nlevel-triggered and re-fires immediately, so on a single-core ARM926\nthe resulting interrupt storm livelocks the CPU.\n\nIt is reproducible when userspace repeatedly opens the front-panel port\n(ttyS1): serial8250_do_set_termios() re-enables interrupts on unlock and\nthe handler then spins forever with iir=0xcc lsr=0x60 ier=0x05, tripping\nthe soft-lockup detector in serial8250_handle_irq_locked().\n\nLPC32xx has no dedicated 8250 glue driver, it\u0027s driven by the generic\n8250_of. Add a hardware specific handle_irq for PORT_LPC3220, wired up\nin of_platform_serial_setup() the same way fsl8250_handle_irq is\ninstalled. The handler follows dw8250_handle_irq(): on an RX timeout\nwith an empty FIFO (LSR.DR and LSR.BI clear) it does one throwaway RHR\nread to clear the condition, then calls serial8250_handle_irq_locked().\nNo real received data is ever discarded, and it is a no-op on healthy\nUARTs which never report a timeout with DR clear.\n\nThis is the same class of bug already worked around in other 8250 drivers;\nsee commit 424d79183af0 (\"serial: 8250_dw: Avoid \"too much work\" from bogus rx timeout interrupt\")\nwhich reports the identical iir=0xcc/lsr=0x60. See also\nUART_RX_TIMEOUT_QUIRK in 8250_omap, and the note in 8250_bcm7271.",
  "id": "GHSA-hpjx-f9r3-xj76",
  "modified": "2026-10-21T15:40:59Z",
  "published": "2026-08-22T18:30:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74653"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1423415471274abda87024967d7fe2206ceee0ea"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3ce24bc4d115336218e59b7e286fd3a79f4fc4c6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7795e8abedc86438cae0454602cbf9038b94bf38"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c321dc5172c8c66e21ffbeeb7a2ebb88ae6fd4c3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cc325ce1c40a111824827532ac132afb3d1c342b"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-74653 (GCVE-0-2026-74653)

Vulnerability from cvelistv5 – Published: 2026-08-22 15:32 – Updated: 2026-10-21 12:46

Title

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

Summary

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.

Severity

No CVSS data available.

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6971 records in the last 180 days details

References

5 references

URL	Tags
https://git.kernel.org/stable/c/cc325ce1c40a11182…
https://git.kernel.org/stable/c/c321dc5172c8c66e2…
https://git.kernel.org/stable/c/3ce24bc4d11533621…
https://git.kernel.org/stable/c/7795e8abedc86438c…
https://git.kernel.org/stable/c/1423415471274abda…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: e6e912c4964ce5976e508881207dfa96d5f856d7 , < cc325ce1c40a111824827532ac132afb3d1c342b (git) Affected: e6e912c4964ce5976e508881207dfa96d5f856d7 , < c321dc5172c8c66e21ffbeeb7a2ebb88ae6fd4c3 (git) Affected: e6e912c4964ce5976e508881207dfa96d5f856d7 , < 3ce24bc4d115336218e59b7e286fd3a79f4fc4c6 (git) Affected: e6e912c4964ce5976e508881207dfa96d5f856d7 , < 7795e8abedc86438cae0454602cbf9038b94bf38 (git) Affected: e6e912c4964ce5976e508881207dfa96d5f856d7 , < 1423415471274abda87024967d7fe2206ceee0ea (git)
Linux	Linux	Affected: 2.6.36 Unaffected: 0 , < 2.6.36 (semver) Unaffected: 6.6.160 , ≤ 6.6.* (semver) Unaffected: 6.12.106 , ≤ 6.12.* (semver) Unaffected: 6.18.45 , ≤ 6.18.* (semver) Unaffected: 7.1.9 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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JSON

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{
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          "programFiles": [
            "drivers/tty/serial/8250/8250_of.c"
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        },
        {
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          "product": "Linux",
          "programFiles": [
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          ],
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          "vendor": "Linux",
          "versions": [
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              "version": "2.6.36"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.106",
              "versionType": "semver"
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            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.45",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
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          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nserial: 8250_of: clear stuck empty-FIFO RX-timeout on LPC32xx\n\nThe NXP LPC32xx UART (PORT_LPC3220) can latch an RX character-timeout\ninterrupt while the RX FIFO is empty: IIR reports UART_IIR_RX_TIMEOUT\n(0x0c) but LSR.DR is clear. A character timeout is only cleared by\nreading RHR, but serial8250_rx_chars() reads RHR only when LSR.DR is\nset, so nothing ever clears the condition. The interrupt is\nlevel-triggered and re-fires immediately, so on a single-core ARM926\nthe resulting interrupt storm livelocks the CPU.\n\nIt is reproducible when userspace repeatedly opens the front-panel port\n(ttyS1): serial8250_do_set_termios() re-enables interrupts on unlock and\nthe handler then spins forever with iir=0xcc lsr=0x60 ier=0x05, tripping\nthe soft-lockup detector in serial8250_handle_irq_locked().\n\nLPC32xx has no dedicated 8250 glue driver, it\u0027s driven by the generic\n8250_of. Add a hardware specific handle_irq for PORT_LPC3220, wired up\nin of_platform_serial_setup() the same way fsl8250_handle_irq is\ninstalled. The handler follows dw8250_handle_irq(): on an RX timeout\nwith an empty FIFO (LSR.DR and LSR.BI clear) it does one throwaway RHR\nread to clear the condition, then calls serial8250_handle_irq_locked().\nNo real received data is ever discarded, and it is a no-op on healthy\nUARTs which never report a timeout with DR clear.\n\nThis is the same class of bug already worked around in other 8250 drivers;\nsee commit 424d79183af0 (\"serial: 8250_dw: Avoid \"too much work\" from bogus rx timeout interrupt\")\nwhich reports the identical iir=0xcc/lsr=0x60. See also\nUART_RX_TIMEOUT_QUIRK in 8250_omap, and the note in 8250_bcm7271."
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          "url": "https://git.kernel.org/stable/c/1423415471274abda87024967d7fe2206ceee0ea"
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    "datePublished": "2026-08-22T15:32:28.521Z",
    "dateReserved": "2026-08-15T05:44:03.923Z",
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    "state": "PUBLISHED"
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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