// For flags

CVE-2021-47491

mm: khugepaged: skip huge page collapse for special files

Severity Score

5.5
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track
*SSVC
Descriptions

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]]

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]]

*Credits: N/A
CVSS Scores
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
* Common Vulnerability Scoring System
SSVC
  • Decision:Track
Exploitation
None
Automatable
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2024-05-22 CVE Reserved
  • 2024-05-22 CVE Published
  • 2024-05-23 EPSS Updated
  • 2024-08-04 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-664: Improper Control of a Resource Through its Lifetime
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Linux
Search vendor "Linux"
 Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
 >= 5.4 < 5.10.78
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.4 < 5.10.78"
en
Affected
Linux
Search vendor "Linux"
 Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
 >= 5.4 < 5.14.16
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.4 < 5.14.16"
en
Affected
Linux
Search vendor "Linux"
 Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
 >= 5.4 < 5.15
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.4 < 5.15"
en
Affected