fkie_cve-2025-21820
Vulnerability from fkie_nvd
Published
2025-02-27 20:16
Modified
2025-03-13 13:15
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: tty: xilinx_uartps: split sysrq handling lockdep detects the following circular locking dependency: CPU 0 CPU 1 ========================== ============================ cdns_uart_isr() printk() uart_port_lock(port) console_lock() cdns_uart_console_write() if (!port->sysrq) uart_port_lock(port) uart_handle_break() port->sysrq = ... uart_handle_sysrq_char() printk() console_lock() The fixed commit attempts to avoid this situation by only taking the port lock in cdns_uart_console_write if port->sysrq unset. However, if (as shown above) cdns_uart_console_write runs before port->sysrq is set, then it will try to take the port lock anyway. This may result in a deadlock. Fix this by splitting sysrq handling into two parts. We use the prepare helper under the port lock and defer handling until we release the lock.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4410dba9807a17a93f649a9f5870ceaf30a675a3Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801cPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9b88a7c4584ba67267a051069b8abe44fc9595b2Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b06f388994500297bb91be60ffaf6825ecfd2afePatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/de5bd24197bd9ee37ec1e379a3d882bbd15c5065Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e22a97700901ba5e8bf8db68056a0d50f9440cae
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *


To clipboard 

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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntty: xilinx_uartps: split sysrq handling\n\nlockdep detects the following circular locking dependency:\n\nCPU 0                      CPU 1\n========================== ============================\ncdns_uart_isr()            printk()\n  uart_port_lock(port)       console_lock()\n\t\t\t     cdns_uart_console_write()\n                               if (!port-\u003esysrq)\n                                 uart_port_lock(port)\n  uart_handle_break()\n    port-\u003esysrq = ...\n  uart_handle_sysrq_char()\n    printk()\n      console_lock()\n\nThe fixed commit attempts to avoid this situation by only taking the\nport lock in cdns_uart_console_write if port-\u003esysrq unset. However, if\n(as shown above) cdns_uart_console_write runs before port-\u003esysrq is set,\nthen it will try to take the port lock anyway. This may result in a\ndeadlock.\n\nFix this by splitting sysrq handling into two parts. We use the prepare\nhelper under the port lock and defer handling until we release the lock."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: tty: xilinx_uartps: la gesti\u00f3n dividido de sysrq lockdep detecta la siguiente dependencia de bloqueo circular: CPU 0 CPU 1 ========================== ============================ cdns_uart_isr() printk() uart_port_lock(port) console_lock() cdns_uart_console_write() if (!port-\u0026gt;sysrq) uart_port_lock(port) uart_handle_break() port-\u0026gt;sysrq = ... uart_handle_sysrq_char() printk() console_lock() The fixed commit attempts to avoid this situation by only taking the port lock in cdns_uart_console_write if port-\u0026gt;sysrq unset. Sin embargo, si (como se muestra arriba) cdns_uart_console_write se ejecuta antes de que port-\u0026gt;sysrq est\u00e9 configurado, entonces intentar\u00e1 tomar el bloqueo del puerto de todos modos. Esto puede resultar en un bloqueo. Solucione esto dividiendo la gesti\u00f3n de sysrq en dos partes. Usamos el asistente de preparaci\u00f3n bajo el bloqueo del puerto y posponemos la gesti\u00f3n hasta que liberemos el bloqueo."
    }
  ],
  "id": "CVE-2025-21820",
  "lastModified": "2025-03-13T13:15:56.413",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
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        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
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  "published": "2025-02-27T20:16:04.520",
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  "vulnStatus": "Modified",
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          "value": "CWE-667"
        }
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      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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