CVE-2024-46706 tty: serial: fsl_lpuart: mark last busy before uart_add_one_port

2024-09-1306:27:33

Linux

www.cve.org

linux kernel

vulnerability

cve-2024-46706

tty

fsl_lpuart

runtime suspend

uart_add_one_port

earlycon

boot hang

uartstat

pm runtime

device probe

console

putchar

runtime suspended

EPSS

Percentile

16.3%

JSON

In the Linux kernel, the following vulnerability has been resolved:

tty: serial: fsl_lpuart: mark last busy before uart_add_one_port

With “earlycon initcall_debug=1 loglevel=8” in bootargs, kernel
sometimes boot hang. It is because normal console still is not ready,
but runtime suspend is called, so early console putchar will hang
in waiting TRDE set in UARTSTAT.

The lpuart driver has auto suspend delay set to 3000ms, but during
uart_add_one_port, a child device serial ctrl will added and probed with
its pm runtime enabled(see serial_ctrl.c).
The runtime suspend call path is:
device_add
|-> bus_probe_device
|->device_initial_probe
|->__device_attach
|-> pm_runtime_get_sync(dev->parent);
|-> pm_request_idle(dev);
|-> pm_runtime_put(dev->parent);

So in the end, before normal console ready, the lpuart get runtime
suspended. And earlycon putchar will hang.

To address the issue, mark last busy just after pm_runtime_enable,
three seconds is long enough to switch from bootconsole to normal
console.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/tty/serial/fsl_lpuart.c"
    ],
    "versions": [
      {
        "version": "43543e6f539b",
        "lessThan": "8eb92cfca6c2",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "43543e6f539b",
        "lessThan": "3ecf625d4acb",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "43543e6f539b",
        "lessThan": "dc98d76a15bc",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/tty/serial/fsl_lpuart.c"
    ],
    "versions": [
      {
        "version": "6.2",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "6.2",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.48",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.10.7",
        "lessThanOrEqual": "6.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.11",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]