CVE-2021-47491

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The intended usecase is to avoid TLB\nmisses for large text segments. But it doesn't restrict the file types\nso a THP could be collapsed for a non-regular file, for example, block\ndevice, if it is opened readonly and mapped with EXEC permission. This\nmay cause bugs, like [1] and [2].\n\nThis is definitely not the intended usecase, so just collapse THP for\nregular files in order to close the attack surface.\n\n[shy828301@gmail.com: fix vm_file check [3]]"}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: mm: khugepaged: omitir el colapso de p\u00e1gina enorme para archivos especiales El THP de solo lectura para sistemas de archivos colapsar\u00e1 el THP para archivos abiertos de solo lectura y asignados con VM_EXEC. El caso de uso previsto es evitar errores de TLB en segmentos de texto grandes. Pero no restringe los tipos de archivos, por lo que un THP podr\u00eda contraerse para un archivo no normal, por ejemplo, un dispositivo de bloqueo, si se abre en modo de solo lectura y se asigna con permiso EXEC. Esto puede causar errores, como [1] y [2]. Definitivamente este no es el caso de uso previsto, as\u00ed que simplemente contraiga THP para archivos normales para cerrar la superficie de ataque. [shy828301@gmail.com: corrige la verificaci\u00f3n de vm_file [3]]"}], "id": "CVE-2021-47491", "lastModified": "2026-06-17T04:17:36.950", "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"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2021-47491", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2024-05-22T18:42:55.199651Z", "version": "2.0.3"}}]}, "published": "2024-05-22T09:15:10.917", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/5fcb6fce74ffa614d964667110cf1a516c48c6d9"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/6d67b2a73b8e3a079c355bab3c1aef7d85a044b8"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/a4aeaa06d45e90f9b279f0b09de84bd00006e733"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/5fcb6fce74ffa614d964667110cf1a516c48c6d9"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/6d67b2a73b8e3a079c355bab3c1aef7d85a044b8"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/a4aeaa06d45e90f9b279f0b09de84bd00006e733"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "NVD-CWE-noinfo"}], "source": "nvd@nist.gov", "type": "Primary"}]}

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