CVE-2025-38614 (GCVE-0-2025-38614)
Vulnerability from cvelistv5
Published
2025-08-19 17:03
Modified
2025-08-28 14:44
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
eventpoll: Fix semi-unbounded recursion
Ensure that epoll instances can never form a graph deeper than
EP_MAX_NESTS+1 links.
Currently, ep_loop_check_proc() ensures that the graph is loop-free and
does some recursion depth checks, but those recursion depth checks don't
limit the depth of the resulting tree for two reasons:
- They don't look upwards in the tree.
- If there are multiple downwards paths of different lengths, only one of
the paths is actually considered for the depth check since commit
28d82dc1c4ed ("epoll: limit paths").
Essentially, the current recursion depth check in ep_loop_check_proc() just
serves to prevent it from recursing too deeply while checking for loops.
A more thorough check is done in reverse_path_check() after the new graph
edge has already been created; this checks, among other things, that no
paths going upwards from any non-epoll file with a length of more than 5
edges exist. However, this check does not apply to non-epoll files.
As a result, it is possible to recurse to a depth of at least roughly 500,
tested on v6.15. (I am unsure if deeper recursion is possible; and this may
have changed with commit 8c44dac8add7 ("eventpoll: Fix priority inversion
problem").)
To fix it:
1. In ep_loop_check_proc(), note the subtree depth of each visited node,
and use subtree depths for the total depth calculation even when a subtree
has already been visited.
2. Add ep_get_upwards_depth_proc() for similarly determining the maximum
depth of an upwards walk.
3. In ep_loop_check(), use these values to limit the total path length
between epoll nodes to EP_MAX_NESTS edges.
References
Impacted products
| Vendor | Product | Version | |||||||
|---|---|---|---|---|---|---|---|---|---|
| ▼ | Linux | Linux |
Version: 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e Version: 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e Version: 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e Version: 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e Version: 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e Version: 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e Version: 22bacca48a1755f79b7e0f192ddb9fbb7fc6e64e Version: 8216e1a0d47cae06a75c42346f19dffe14e42d57 Version: 28a92748aa4bc57d35e7b079498b0ac2e7610a37 Version: 7eebcd4792c5a341559aed327b6afecbb1c46402 Version: 0eccd188cfeaf857a26f2d72941d27d298cf6a54 Version: a72affdbb09f3f24f64ffcbbdf62c2e57c58f379 |
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|
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{
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"vendor": "Linux",
"versions": [
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"version": "0",
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{
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{
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{
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\neventpoll: Fix semi-unbounded recursion\n\nEnsure that epoll instances can never form a graph deeper than\nEP_MAX_NESTS+1 links.\n\nCurrently, ep_loop_check_proc() ensures that the graph is loop-free and\ndoes some recursion depth checks, but those recursion depth checks don\u0027t\nlimit the depth of the resulting tree for two reasons:\n\n - They don\u0027t look upwards in the tree.\n - If there are multiple downwards paths of different lengths, only one of\n the paths is actually considered for the depth check since commit\n 28d82dc1c4ed (\"epoll: limit paths\").\n\nEssentially, the current recursion depth check in ep_loop_check_proc() just\nserves to prevent it from recursing too deeply while checking for loops.\n\nA more thorough check is done in reverse_path_check() after the new graph\nedge has already been created; this checks, among other things, that no\npaths going upwards from any non-epoll file with a length of more than 5\nedges exist. However, this check does not apply to non-epoll files.\n\nAs a result, it is possible to recurse to a depth of at least roughly 500,\ntested on v6.15. (I am unsure if deeper recursion is possible; and this may\nhave changed with commit 8c44dac8add7 (\"eventpoll: Fix priority inversion\nproblem\").)\n\nTo fix it:\n\n1. In ep_loop_check_proc(), note the subtree depth of each visited node,\nand use subtree depths for the total depth calculation even when a subtree\nhas already been visited.\n2. Add ep_get_upwards_depth_proc() for similarly determining the maximum\ndepth of an upwards walk.\n3. In ep_loop_check(), use these values to limit the total path length\nbetween epoll nodes to EP_MAX_NESTS edges."
}
],
"providerMetadata": {
"dateUpdated": "2025-08-28T14:44:11.684Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
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"url": "https://git.kernel.org/stable/c/71379495ab70eaba19224bd71b5b9b399eb85e04"
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{
"url": "https://git.kernel.org/stable/c/1b13b033062824495554e836a1ff5f85ccf6b039"
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{
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{
"url": "https://git.kernel.org/stable/c/7a2125962c42d5336ca0495a9ce4cb38a63e9161"
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{
"url": "https://git.kernel.org/stable/c/ea5f97dbdcb1651581a22bd10afd2f0dd9dc11d6"
},
{
"url": "https://git.kernel.org/stable/c/3542c90797bc3ab83ebab54b737d751cf3682036"
},
{
"url": "https://git.kernel.org/stable/c/f2e467a48287c868818085aa35389a224d226732"
}
],
"title": "eventpoll: Fix semi-unbounded recursion",
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"assignerShortName": "Linux",
"cveId": "CVE-2025-38614",
"datePublished": "2025-08-19T17:03:56.348Z",
"dateReserved": "2025-04-16T04:51:24.029Z",
"dateUpdated": "2025-08-28T14:44:11.684Z",
"state": "PUBLISHED"
},
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"nvd": "{\"cve\":{\"id\":\"CVE-2025-38614\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-08-19T17:15:40.040\",\"lastModified\":\"2025-08-28T15:15:55.647\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\neventpoll: Fix semi-unbounded recursion\\n\\nEnsure that epoll instances can never form a graph deeper than\\nEP_MAX_NESTS+1 links.\\n\\nCurrently, ep_loop_check_proc() ensures that the graph is loop-free and\\ndoes some recursion depth checks, but those recursion depth checks don\u0027t\\nlimit the depth of the resulting tree for two reasons:\\n\\n - They don\u0027t look upwards in the tree.\\n - If there are multiple downwards paths of different lengths, only one of\\n the paths is actually considered for the depth check since commit\\n 28d82dc1c4ed (\\\"epoll: limit paths\\\").\\n\\nEssentially, the current recursion depth check in ep_loop_check_proc() just\\nserves to prevent it from recursing too deeply while checking for loops.\\n\\nA more thorough check is done in reverse_path_check() after the new graph\\nedge has already been created; this checks, among other things, that no\\npaths going upwards from any non-epoll file with a length of more than 5\\nedges exist. However, this check does not apply to non-epoll files.\\n\\nAs a result, it is possible to recurse to a depth of at least roughly 500,\\ntested on v6.15. (I am unsure if deeper recursion is possible; and this may\\nhave changed with commit 8c44dac8add7 (\\\"eventpoll: Fix priority inversion\\nproblem\\\").)\\n\\nTo fix it:\\n\\n1. In ep_loop_check_proc(), note the subtree depth of each visited node,\\nand use subtree depths for the total depth calculation even when a subtree\\nhas already been visited.\\n2. Add ep_get_upwards_depth_proc() for similarly determining the maximum\\ndepth of an upwards walk.\\n3. In ep_loop_check(), use these values to limit the total path length\\nbetween epoll nodes to EP_MAX_NESTS edges.\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: eventpoll: Arregla recursi\u00f3n semi-ilimitada Garantiza que las instancias de epoll nunca puedan formar un grafo m\u00e1s profundo que los enlaces EP_MAX_NESTS+1. Actualmente, ep_loop_check_proc() garantiza que el grafo no tenga bucles y realiza algunas comprobaciones de profundidad de recursi\u00f3n, pero esas comprobaciones de profundidad de recursi\u00f3n no limitan la profundidad del \u00e1rbol resultante por dos razones: - No miran hacia arriba en el \u00e1rbol. - Si hay m\u00faltiples rutas descendentes de diferentes longitudes, solo una de las rutas se considera realmente para la comprobaci\u00f3n de profundidad desde el commit 28d82dc1c4ed (\\\"epoll: limitar rutas\\\"). Esencialmente, la comprobaci\u00f3n de profundidad de recursi\u00f3n actual en ep_loop_check_proc() solo sirve para evitar que recurra demasiado profundamente mientras comprueba bucles. Se realiza una comprobaci\u00f3n m\u00e1s exhaustiva en reverse_path_check() despu\u00e9s de que ya se haya creado el nuevo borde del grafo; Esto comprueba, entre otras cosas, que no existan rutas ascendentes desde ning\u00fan archivo que no sea epoll con una longitud de m\u00e1s de 5 aristas. Sin embargo, esta comprobaci\u00f3n no se aplica a los archivos que no son epoll. Como resultado, es posible realizar una recursi\u00f3n a una profundidad de al menos aproximadamente 500, probada en la versi\u00f3n v6.15. (No estoy seguro de si es posible una recursi\u00f3n m\u00e1s profunda; esto puede haber cambiado con el commit 8c44dac8add7 (\\\"eventpoll: Correcci\u00f3n del problema de inversi\u00f3n de prioridad\\\")). Para solucionarlo: 1. En ep_loop_check_proc(), anote la profundidad del sub\u00e1rbol de cada nodo visitado y utilice las profundidades del sub\u00e1rbol para el c\u00e1lculo de la profundidad total, incluso si ya se ha visitado un sub\u00e1rbol. 2. A\u00f1ada ep_get_upwards_depth_proc() para determinar de forma similar la profundidad m\u00e1xima de un recorrido ascendente. 3. En ep_loop_check(), utilice estos valores para limitar la longitud total de la ruta entre nodos epoll a EP_MAX_NESTS aristas. \"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1b13b033062824495554e836a1ff5f85ccf6b039\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/2a0c0c974bea9619c6f41794775ae4b97530e0e6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/3542c90797bc3ab83ebab54b737d751cf3682036\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/71379495ab70eaba19224bd71b5b9b399eb85e04\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/7a2125962c42d5336ca0495a9ce4cb38a63e9161\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ea5f97dbdcb1651581a22bd10afd2f0dd9dc11d6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f2e467a48287c868818085aa35389a224d226732\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
}
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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