CVE-2021-47491

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2021-47491
In the Linux kernel, the following vulnerability has been resolved: mm: khugepaged: skip huge page collapse for special files The read-only THP for filesystems will collapse THP for files opened readonly and mapped with VM_EXEC. The intended usecase is to avoid TLB misses for large text segments. But it doesn't restrict the file types so a THP could be collapsed for a non-regular file, for example, block device, if it is opened readonly and mapped with EXEC permission. This may cause bugs, like [1] and [2]. This is definitely not the intended usecase, so just collapse THP for regular files in order to close the attack surface. [shy828301@gmail.com: fix vm_file check [3]]

5.5 /10

CVSS v3 : MEDIUM

V3 Legend

Vector :

Exploitability : 1.8 / Impact : 3.6

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References
Link Resource
https://git.kernel.org/stable/c/5fcb6fce74ffa614d964667110cf1a516c48c6d9 Patch
https://git.kernel.org/stable/c/6d67b2a73b8e3a079c355bab3c1aef7d85a044b8 Patch
https://git.kernel.org/stable/c/a4aeaa06d45e90f9b279f0b09de84bd00006e733 Patch
https://git.kernel.org/stable/c/5fcb6fce74ffa614d964667110cf1a516c48c6d9 Patch
https://git.kernel.org/stable/c/6d67b2a73b8e3a079c355bab3c1aef7d85a044b8 Patch
https://git.kernel.org/stable/c/a4aeaa06d45e90f9b279f0b09de84bd00006e733 Patch
Configurations

Configuration 1 (hide)

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc6:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc7:*:*:*:*:*:*
History

29 Sep 2025, 16:37

Type Values Removed Values Added
CPE cpe:2.3:o:linux:linux_kernel:5.15:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc7:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.15:rc6:*:*:*:*:*:*
CWE NVD-CWE-noinfo
References () https://git.kernel.org/stable/c/5fcb6fce74ffa614d964667110cf1a516c48c6d9 - () https://git.kernel.org/stable/c/5fcb6fce74ffa614d964667110cf1a516c48c6d9 - Patch
References () https://git.kernel.org/stable/c/6d67b2a73b8e3a079c355bab3c1aef7d85a044b8 - () https://git.kernel.org/stable/c/6d67b2a73b8e3a079c355bab3c1aef7d85a044b8 - Patch
References () https://git.kernel.org/stable/c/a4aeaa06d45e90f9b279f0b09de84bd00006e733 - () https://git.kernel.org/stable/c/a4aeaa06d45e90f9b279f0b09de84bd00006e733 - Patch
CVSS v2 : unknown
v3 : unknown 		v2 : unknown
v3 : 5.5
First Time Linux linux Kernel
Linux

21 Nov 2024, 06:36

Type Values Removed Values Added
Summary
  • (es) En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: mm: khugepaged: omitir el colapso de página enorme para archivos especiales El THP de solo lectura para sistemas de archivos colapsará 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 podría 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, así que simplemente contraiga THP para archivos normales para cerrar la superficie de ataque. [shy828301@gmail.com: corrige la verificación de vm_file [3]]
References () https://git.kernel.org/stable/c/5fcb6fce74ffa614d964667110cf1a516c48c6d9 - () https://git.kernel.org/stable/c/5fcb6fce74ffa614d964667110cf1a516c48c6d9 -
References () https://git.kernel.org/stable/c/6d67b2a73b8e3a079c355bab3c1aef7d85a044b8 - () https://git.kernel.org/stable/c/6d67b2a73b8e3a079c355bab3c1aef7d85a044b8 -
References () https://git.kernel.org/stable/c/a4aeaa06d45e90f9b279f0b09de84bd00006e733 - () https://git.kernel.org/stable/c/a4aeaa06d45e90f9b279f0b09de84bd00006e733 -

22 May 2024, 09:15

Type Values Removed Values Added
New CVE
Information

Published : 2024-05-22 09:15

Updated : 2025-09-29 16:37

NVD link : CVE-2021-47491

Mitre link : CVE-2021-47491

CVE.ORG link : CVE-2021-47491

JSON object : View

Products Affected

linux

  • linux_kernel
CWE
NVD-CWE-noinfo