CVE-2025-38282 (GCVE-0-2025-38282)
Vulnerability from cvelistv5
Published
2025-07-10 07:42
Modified
2025-11-03 17:36
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: kernfs: Relax constraint in draining guard The active reference lifecycle provides the break/unbreak mechanism but the active reference is not truly active after unbreak -- callers don't use it afterwards but it's important for proper pairing of kn->active counting. Assuming this mechanism is in place, the WARN check in kernfs_should_drain_open_files() is too sensitive -- it may transiently catch those (rightful) callers between kernfs_unbreak_active_protection() and kernfs_put_active() as found out by Chen Ridong: kernfs_remove_by_name_ns kernfs_get_active // active=1 __kernfs_remove // active=0x80000002 kernfs_drain ... wait_event //waiting (active == 0x80000001) kernfs_break_active_protection // active = 0x80000001 // continue kernfs_unbreak_active_protection // active = 0x80000002 ... kernfs_should_drain_open_files // warning occurs kernfs_put_active To avoid the false positives (mind panic_on_warn) remove the check altogether. (This is meant as quick fix, I think active reference break/unbreak may be simplified with larger rework.)
References
Impacted products
Vendor Product Version
Linux Linux Version: bdb2fd7fc56e197a63c0b0e7e07d25d5e20e7c72
Version: bdb2fd7fc56e197a63c0b0e7e07d25d5e20e7c72
Version: bdb2fd7fc56e197a63c0b0e7e07d25d5e20e7c72
Version: bdb2fd7fc56e197a63c0b0e7e07d25d5e20e7c72
Version: bdb2fd7fc56e197a63c0b0e7e07d25d5e20e7c72
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nkernfs: Relax constraint in draining guard\n\nThe active reference lifecycle provides the break/unbreak mechanism but\nthe active reference is not truly active after unbreak -- callers don\u0027t\nuse it afterwards but it\u0027s important for proper pairing of kn-\u003eactive\ncounting. Assuming this mechanism is in place, the WARN check in\nkernfs_should_drain_open_files() is too sensitive -- it may transiently\ncatch those (rightful) callers between\nkernfs_unbreak_active_protection() and kernfs_put_active() as found out by Chen\nRidong:\n\n\tkernfs_remove_by_name_ns\tkernfs_get_active // active=1\n\t__kernfs_remove\t\t\t\t\t  // active=0x80000002\n\tkernfs_drain\t\t\t...\n\twait_event\n\t//waiting (active == 0x80000001)\n\t\t\t\t\tkernfs_break_active_protection\n\t\t\t\t\t// active = 0x80000001\n\t// continue\n\t\t\t\t\tkernfs_unbreak_active_protection\n\t\t\t\t\t// active = 0x80000002\n\t...\n\tkernfs_should_drain_open_files\n\t// warning occurs\n\t\t\t\t\tkernfs_put_active\n\nTo avoid the false positives (mind panic_on_warn) remove the check altogether.\n(This is meant as quick fix, I think active reference break/unbreak may be\nsimplified with larger rework.)"
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    "nvd": "{\"cve\":{\"id\":\"CVE-2025-38282\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-07-10T08:15:26.610\",\"lastModified\":\"2025-11-03T18:16:12.163\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nkernfs: Relax constraint in draining guard\\n\\nThe active reference lifecycle provides the break/unbreak mechanism but\\nthe active reference is not truly active after unbreak -- callers don\u0027t\\nuse it afterwards but it\u0027s important for proper pairing of kn-\u003eactive\\ncounting. Assuming this mechanism is in place, the WARN check in\\nkernfs_should_drain_open_files() is too sensitive -- it may transiently\\ncatch those (rightful) callers between\\nkernfs_unbreak_active_protection() and kernfs_put_active() as found out by Chen\\nRidong:\\n\\n\\tkernfs_remove_by_name_ns\\tkernfs_get_active // active=1\\n\\t__kernfs_remove\\t\\t\\t\\t\\t  // active=0x80000002\\n\\tkernfs_drain\\t\\t\\t...\\n\\twait_event\\n\\t//waiting (active == 0x80000001)\\n\\t\\t\\t\\t\\tkernfs_break_active_protection\\n\\t\\t\\t\\t\\t// active = 0x80000001\\n\\t// continue\\n\\t\\t\\t\\t\\tkernfs_unbreak_active_protection\\n\\t\\t\\t\\t\\t// active = 0x80000002\\n\\t...\\n\\tkernfs_should_drain_open_files\\n\\t// warning occurs\\n\\t\\t\\t\\t\\tkernfs_put_active\\n\\nTo avoid the false positives (mind panic_on_warn) remove the check altogether.\\n(This is meant as quick fix, I think active reference break/unbreak may be\\nsimplified with larger rework.)\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: kernfs: relajar restricci\u00f3n en el drenaje de la protecci\u00f3n El ciclo de vida de la referencia activa proporciona el mecanismo de interrupci\u00f3n/desconexi\u00f3n, pero la referencia activa no est\u00e1 verdaderamente activa despu\u00e9s de la conexi\u00f3n; los llamadores no la usan despu\u00e9s, pero es importante para el emparejamiento adecuado del conteo kn-\u0026gt;activo. Suponiendo que este mecanismo est\u00e1 en su lugar, la comprobaci\u00f3n WARN en kernfs_should_drain_open_files() es demasiado sensible - puede atrapar transitoriamente a aquellos llamadores (leg\u00edtimos) entre kernfs_unbreak_active_protection() y kernfs_put_active() como descubri\u00f3 Chen Ridong: kernfs_remove_by_name_ns kernfs_get_active // active=1 __kernfs_remove // active=0x80000002 kernfs_drain ... wait_event //waiting (active == 0x80000001) kernfs_break_active_protection // active = 0x80000001 // continuar kernfs_unbreak_active_protection // active = 0x80000002 ... kernfs_should_drain_open_files // ocurre una advertencia kernfs_put_active Para evitar los falsos positivos (tenga en cuenta \\\"panic_on_warn\\\"), elimine la comprobaci\u00f3n por completo. (Esto es una soluci\u00f3n r\u00e1pida; creo que la interrupci\u00f3n/desconexi\u00f3n de referencias activas se puede simplificar con una revisi\u00f3n m\u00e1s exhaustiva).\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/071d8e4c2a3b0999a9b822e2eb8854784a350f8a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/2d6a67c2b3b87808a347dc1047b520a9dd177a4f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/6bfb154f95d5f0ab7ed056f23aba8c1a94cb3927\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/6c81f1c7812c61f187bed1b938f1d2e391d503ab\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/72275c888f8962b406ee9c6885c79bf68cca5a63\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\"}]}}"
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