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However, if a class is created with classid TC_H_ROOT, the\ntraversal terminates prematurely at this class instead of reaching the\nactual root qdisc, causing parent statistics to be incorrectly maintained.\nIn case of DRR, this could lead to a crash as reported by Mingi Cho.\n\nPrevent the creation of any Qdisc class with classid TC_H_ROOT\n(0xFFFFFFFF) across all qdisc types, as suggested by Jamal."}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: net_sched: Impide la creaci\u00f3n de clases con TC_H_ROOT La funci\u00f3n qdisc_tree_reduce_backlog() usa TC_H_ROOT como condici\u00f3n de terminaci\u00f3n al recorrer el \u00e1rbol qdisc para actualizar los contadores de backlog primarios. Sin embargo, si se crea una clase con classid TC_H_ROOT, el recorrido termina prematuramente en esta clase en lugar de alcanzar la qdisc root real, lo que provoca que las estad\u00edsticas primarias se mantengan incorrectamente. En caso de DRR, esto podr\u00eda provocar un fallo como lo inform\u00f3 Mingi Cho. 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{"bugzilla": {"description": "kernel: net_sched: Prevent creation of classes with TC_H_ROOT", "id": "2356598", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2356598"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-703", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nnet_sched: Prevent creation of classes with TC_H_ROOT\nThe function qdisc_tree_reduce_backlog() uses TC_H_ROOT as a termination\ncondition when traversing up the qdisc tree to update parent backlog\ncounters. However, if a class is created with classid TC_H_ROOT, the\ntraversal terminates prematurely at this class instead of reaching the\nactual root qdisc, causing parent statistics to be incorrectly maintained.\nIn case of DRR, this could lead to a crash as reported by Mingi Cho.\nPrevent the creation of any Qdisc class with classid TC_H_ROOT\n(0xFFFFFFFF) across all qdisc types, as suggested by Jamal."], "name": "CVE-2025-21971", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2025-04-01T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-21971\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-21971\nhttps://lore.kernel.org/linux-cve-announce/2025040146-CVE-2025-21971-d17c@gregkh/T"], "threat_severity": "Moderate"}

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