CVE-2021-47214

{"id": "CVE-2021-47214", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "[email protected]", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 1.8}]}, "published": "2024-04-10T19:15:48.680", "references": [{"url": "https://git.kernel.org/stable/c/b5069d44e2fbc4a9093d005b3ef0949add3dd27e", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/cc30042df6fcc82ea18acf0dace831503e60a0b7", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/b5069d44e2fbc4a9093d005b3ef0949add3dd27e", "tags": ["Patch"], "source": "af854a3a-2127-422b-91ae-364da2661108"}, {"url": "https://git.kernel.org/stable/c/cc30042df6fcc82ea18acf0dace831503e60a0b7", "tags": ["Patch"], "source": "af854a3a-2127-422b-91ae-364da2661108"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "[email protected]", "description": [{"lang": "en", "value": "CWE-401"}]}], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nhugetlb, userfaultfd: fix reservation restore on userfaultfd error\n\nCurrently in the is_continue case in hugetlb_mcopy_atomic_pte(), if we\nbail out using \"goto out_release_unlock;\" in the cases where idx >=\nsize, or !huge_pte_none(), the code will detect that new_pagecache_page\n== false, and so call restore_reserve_on_error(). In this case I see\nrestore_reserve_on_error() delete the reservation, and the following\ncall to remove_inode_hugepages() will increment h->resv_hugepages\ncausing a 100% reproducible leak.\n\nWe should treat the is_continue case similar to adding a page into the\npagecache and set new_pagecache_page to true, to indicate that there is\nno reservation to restore on the error path, and we need not call\nrestore_reserve_on_error(). Rename new_pagecache_page to\npage_in_pagecache to make that clear."}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: hugetlb, userfaultfd: se corrige el error de restauraci\u00f3n de reserva en userfaultfd Actualmente, en el caso is_continue en hugetlb_mcopy_atomic_pte(), si salimos usando \"goto out_release_unlock;\" en los casos donde idx >= size, o !huge_pte_none(), el c\u00f3digo detectar\u00e1 que new_pagecache_page == false, y por lo tanto llamar\u00e1 a restore_reserve_on_error(). En este caso, veo que restore_reserve_on_error() elimina la reserva, y la siguiente llamada a remove_inode_hugepages() incrementar\u00e1 h->resv_hugepages causando una fuga 100% reproducible. Deber\u00edamos tratar el caso is_continue de forma similar a agregar una p\u00e1gina al pagecache y establecer new_pagecache_page en true, para indicar que no hay ninguna reserva para restaurar en la ruta del error, y no necesitamos llamar a restore_reserve_on_error(). Cambie el nombre new_pagecache_page a page_in_pagecache para que quede claro."}], "lastModified": "2025-03-27T21:05:27.253", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "53E796CA-D377-4F91-8FF4-33D9CAC9A4B8", "versionEndExcluding": "5.15.5", "versionStartIncluding": "5.14"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:5.13.13:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "6047C65C-29BB-4EDB-B410-FA269D2877D5"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:5.16:rc1:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "357AA433-37E8-4323-BFB2-3038D6E4B414"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}