fkie_cve-2024-49940
Vulnerability from fkie_nvd
Published
2024-10-21 18:15
Modified
2024-11-13 13:26
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
l2tp: prevent possible tunnel refcount underflow
When a session is created, it sets a backpointer to its tunnel. When
the session refcount drops to 0, l2tp_session_free drops the tunnel
refcount if session->tunnel is non-NULL. However, session->tunnel is
set in l2tp_session_create, before the tunnel refcount is incremented
by l2tp_session_register, which leaves a small window where
session->tunnel is non-NULL when the tunnel refcount hasn't been
bumped.
Moving the assignment to l2tp_session_register is trivial but
l2tp_session_create calls l2tp_session_set_header_len which uses
session->tunnel to get the tunnel's encap. Add an encap arg to
l2tp_session_set_header_len to avoid using session->tunnel.
If l2tpv3 sessions have colliding IDs, it is possible for
l2tp_v3_session_get to race with l2tp_session_register and fetch a
session which doesn't yet have session->tunnel set. Add a check for
this case.
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| linux | linux_kernel | * |
{
"configurations": [
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"nodes": [
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"matchCriteriaId": "6D5FF9C2-A011-4A64-B614-F9244ED2EA0D",
"versionEndExcluding": "6.11.3",
"vulnerable": true
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"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nl2tp: prevent possible tunnel refcount underflow\n\nWhen a session is created, it sets a backpointer to its tunnel. When\nthe session refcount drops to 0, l2tp_session_free drops the tunnel\nrefcount if session-\u003etunnel is non-NULL. However, session-\u003etunnel is\nset in l2tp_session_create, before the tunnel refcount is incremented\nby l2tp_session_register, which leaves a small window where\nsession-\u003etunnel is non-NULL when the tunnel refcount hasn\u0027t been\nbumped.\n\nMoving the assignment to l2tp_session_register is trivial but\nl2tp_session_create calls l2tp_session_set_header_len which uses\nsession-\u003etunnel to get the tunnel\u0027s encap. Add an encap arg to\nl2tp_session_set_header_len to avoid using session-\u003etunnel.\n\nIf l2tpv3 sessions have colliding IDs, it is possible for\nl2tp_v3_session_get to race with l2tp_session_register and fetch a\nsession which doesn\u0027t yet have session-\u003etunnel set. Add a check for\nthis case."
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: l2tp: evitar un posible desbordamiento del recuento de referencias del t\u00fanel Cuando se crea una sesi\u00f3n, establece un puntero hacia atr\u00e1s a su t\u00fanel. Cuando el recuento de referencias de la sesi\u00f3n cae a 0, l2tp_session_free descarta el recuento de referencias del t\u00fanel si session-\u0026gt;tunnel no es NULL. Sin embargo, session-\u0026gt;tunnel se establece en l2tp_session_create, antes de que el recuento de referencias del t\u00fanel se incremente mediante l2tp_session_register, lo que deja una peque\u00f1a ventana donde session-\u0026gt;tunnel no es NULL cuando el recuento de referencias del t\u00fanel no se ha incrementado. Mover la asignaci\u00f3n a l2tp_session_register es trivial, pero l2tp_session_create llama a l2tp_session_set_header_len, que usa session-\u0026gt;tunnel para obtener el encap del t\u00fanel. Agregue un argumento de encap a l2tp_session_set_header_len para evitar usar session-\u0026gt;tunnel. Si las sesiones l2tpv3 tienen identificadores en conflicto, es posible que l2tp_v3_session_get compita con l2tp_session_register y obtenga una sesi\u00f3n que a\u00fan no tenga configurado session-\u0026gt;tunnel. Agregue una verificaci\u00f3n para este caso."
}
],
"id": "CVE-2024-49940",
"lastModified": "2024-11-13T13:26:01.343",
"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": "2024-10-21T18:15:15.703",
"references": [
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
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"url": "https://git.kernel.org/stable/c/24256415d18695b46da06c93135f5b51c548b950"
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"url": "https://git.kernel.org/stable/c/f7415e60c25a6108cd7955a20b2e66b6251ffe02"
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"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Analyzed",
"weaknesses": [
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"description": [
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"lang": "en",
"value": "NVD-CWE-noinfo"
}
],
"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
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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.