CVE-2025-21820 (GCVE-0-2025-21820)

Vulnerability from cvelistv5 – Published: 2025-02-27 20:04 – Updated: 2025-11-03 20:59
VLAI?
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.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 74ea66d4ca061a3cd4c0e924e51b60e924644852 , < e22a97700901ba5e8bf8db68056a0d50f9440cae (git)
Affected: 74ea66d4ca061a3cd4c0e924e51b60e924644852 , < de5bd24197bd9ee37ec1e379a3d882bbd15c5065 (git)
Affected: 74ea66d4ca061a3cd4c0e924e51b60e924644852 , < 8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801c (git)
Affected: 74ea66d4ca061a3cd4c0e924e51b60e924644852 , < 9b88a7c4584ba67267a051069b8abe44fc9595b2 (git)
Affected: 74ea66d4ca061a3cd4c0e924e51b60e924644852 , < 4410dba9807a17a93f649a9f5870ceaf30a675a3 (git)
Affected: 74ea66d4ca061a3cd4c0e924e51b60e924644852 , < b06f388994500297bb91be60ffaf6825ecfd2afe (git)
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    Linux Linux Affected: 4.6
Unaffected: 0 , < 4.6 (semver)
Unaffected: 5.15.179 , ≤ 5.15.* (semver)
Unaffected: 6.1.129 , ≤ 6.1.* (semver)
Unaffected: 6.6.78 , ≤ 6.6.* (semver)
Unaffected: 6.12.14 , ≤ 6.12.* (semver)
Unaffected: 6.13.3 , ≤ 6.13.* (semver)
Unaffected: 6.14 , ≤ * (original_commit_for_fix)
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          "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."
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    "nvd": "{\"cve\":{\"id\":\"CVE-2025-21820\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-02-27T20:16:04.520\",\"lastModified\":\"2025-11-03T21:19:12.597\",\"vulnStatus\":\"Modified\",\"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. 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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. 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Sightings

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  • 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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