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Considered\ntoo specific a use case to extend such a struct, though this would\nbe a resilient fix and address other previous and potential future\nDOS bugs like the one described in loopy fun [2].\n\n2) Restrict netem_enqueue recursion depth like in act_mirred with a\nper cpu variable. However, netem_dequeue can call enqueue on its\nchild, and the depth restriction could be bypassed if the child is a\nnetem.\n\n3) Use the same approach as in 2, but add metadata in netem_skb_cb\nto handle the netem_dequeue case and track a packet's involvement\nin duplication. This is an overly complex approach, and Jamal\nnotes that the skb cb can be overwritten to circumvent this\nsafeguard.\n\n4) Prevent the addition of a netem to a qdisc tree if its ancestral\npath contains a netem. 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Considered\ntoo specific a use case to extend such a struct, though this would\nbe a resilient fix and address other previous and potential future\nDOS bugs like the one described in loopy fun [2].\n\n2) Restrict netem_enqueue recursion depth like in act_mirred with a\nper cpu variable. However, netem_dequeue can call enqueue on its\nchild, and the depth restriction could be bypassed if the child is a\nnetem.\n\n3) Use the same approach as in 2, but add metadata in netem_skb_cb\nto handle the netem_dequeue case and track a packet's involvement\nin duplication. This is an overly complex approach, and Jamal\nnotes that the skb cb can be overwritten to circumvent this\nsafeguard.\n\n4) Prevent the addition of a netem to a qdisc tree if its ancestral\npath contains a netem. However, filters and actions can cause a\npacket to change paths when re-enqueued to the root from netem\nduplication, leading us to the current solution: prevent a\nduplicating netem from inhabiting the same tree as other netems.\n\n[1] https://lore.kernel.org/netdev/8DuRWwfqjoRDLDmBMlIfbrsZg9Gx50DHJc1ilxsEBNe2D6NMoigR_eIRIG0LOjMc3r10nUUZtArXx4oZBIdUfZQrwjcQhdinnMis_0G7VEk=@willsroot.io/\n[2] https://lwn.net/Articles/719297/"}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: net/sched: Restringir las condiciones para agregar netems duplicados al \u00e1rbol qdisc La l\u00f3gica de prevenci\u00f3n de duplicaci\u00f3n de netem_enqueue se rompe cuando un netem reside en un \u00e1rbol qdisc con otros netems: esto puede provocar un bloqueo suave y un bucle OOM en netem_dequeue, como se ve en [1]. Aseg\u00farese de que un netem duplicado no pueda existir en un \u00e1rbol con otros netems. Enfoques previos sugeridos en discusiones en orden cronol\u00f3gico: 1) Rastrear el estado de duplicaci\u00f3n o ttl en la estructura sk_buff. Se considera un caso de uso demasiado espec\u00edfico para extender dicha estructura, aunque esta ser\u00eda una soluci\u00f3n resiliente y abordar\u00eda otros errores de DOS anteriores y futuros potenciales como el descrito en loopy fun [2]. 2) Restringir la profundidad de recursi\u00f3n de netem_enqueue como en act_mirred con una variable por CPU. Sin embargo, netem_dequeue puede ejecutar la funci\u00f3n en cola en su elemento secundario, y la restricci\u00f3n de profundidad podr\u00eda omitirse si el elemento secundario es un netem. 3) Use el mismo enfoque que en el punto 2, pero agregue metadatos en netem_skb_cb para gestionar el caso de netem_dequeue y rastrear la participaci\u00f3n de un paquete en la duplicaci\u00f3n. Este es un enfoque excesivamente complejo, y Jamal se\u00f1ala que el skb_cb puede sobrescribirse para eludir esta protecci\u00f3n. 4) Evite la adici\u00f3n de un netem a un \u00e1rbol qdisc si su ruta ancestral contiene un netem. Sin embargo, los filtros y las acciones pueden provocar que un paquete cambie de ruta al volver a encolarse a la ra\u00edz desde la duplicaci\u00f3n de netem, lo que nos lleva a la soluci\u00f3n actual: evitar que un netem duplicado ocupe el mismo \u00e1rbol que otros netems. [1] https://lore.kernel.org/netdev/8DuRWwfqjoRDLDmBMlIfbrsZg9Gx50DHJc1ilxsEBNe2D6NMoigR_eIRIG0LOjMc3r10nUUZtArXx4oZBIdUfZQrwjcQhdinnMis_0G7VEk=@willsroot.io/ [2] https://lwn.net/Articles/719297/"}], "id": "CVE-2025-38553", "lastModified": "2026-01-08T20:49:12.590", "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"}, "exploitabilityScore": 1.8, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2025-08-19T06:15:33.407", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/09317dfb681ac5a96fc69bea0c54441cf91b8270"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/103c4e27ec9f5fe53022e46e976abf52c7221baf"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/250f8796006c0f2bc638ce545f601d49ae8d528b"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/325f5ec67cc0a77f2d0d453445b9857f1cd06c76"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/795cb393e38977aa991e70a9363da0ee734b2114"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/ad340a4b4adb855b18b3666f26ad65c8968e2deb"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/cab2809944989889f88a1a8b5cff1c78460c72cb"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/ec8e0e3d7adef940cdf9475e2352c0680189d14e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/f088b6ebe8797a3f948d2cae47f34bfb45cc6522"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Third Party Advisory", "Mailing List"], "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Third Party Advisory", "Mailing List"], "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-667"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: net/sched: Restrict conditions for adding duplicating netems to qdisc tree", "id": "2389333", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2389333"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "details": ["No description is available for this CVE."], "name": "CVE-2025-38553", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Under investigation", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2025-08-19T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-38553\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-38553\nhttps://lore.kernel.org/linux-cve-announce/2025081956-CVE-2025-38553-4ecb@gregkh/T"], "threat_severity": "Important"}

{"created": "2025-08-21T12:32:03.299789+00:00", "updated": "2025-08-21T12:32:03.299840+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}