CVE-2021-47214

In the Linux kernel, the following vulnerability has been resolved: hugetlb, userfaultfd: fix reservation restore on userfaultfd error Currently in the is_continue case in hugetlb_mcopy_atomic_pte(), if we bail out using "goto out_release_unlock;" in the cases where idx >= size, or !huge_pte_none(), the code will detect that new_pagecache_page == false, and so call restore_reserve_on_error(). In this case I see restore_reserve_on_error() delete the reservation, and the following call to remove_inode_hugepages() will increment h->resv_hugepages causing a 100% reproducible leak. We should treat the is_continue case similar to adding a page into the pagecache and set new_pagecache_page to true, to indicate that there is no reservation to restore on the error path, and we need not call restore_reserve_on_error(). Rename new_pagecache_page to page_in_pagecache to make that clear.

CVSS v3 5.5 MEDIUM

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/b5069d44e2fbc4a9093d005b3ef0949add3dd27e	Patch
https://git.kernel.org/stable/c/cc30042df6fcc82ea18acf0dace831503e60a0b7	Patch
https://git.kernel.org/stable/c/b5069d44e2fbc4a9093d005b3ef0949add3dd27e	Patch
https://git.kernel.org/stable/c/cc30042df6fcc82ea18acf0dace831503e60a0b7	Patch

Configurations

Configuration 1 (hide)

OR	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel:5.13.13:::::::*
	cpe:2.3:o:linux:linux_kernel:5.16:rc1::::::

History

27 Mar 2025, 21:05

Type	Values Removed	Values Added
CPE		cpe:2.3:o:linux:linux_kernel:::::::: cpe:2.3:o:linux:linux_kernel:5.16:rc1:::::: cpe:2.3:o:linux:linux_kernel:5.13.13:::::::*
First Time		Linux Linux linux Kernel
References	~~() https://git.kernel.org/stable/c/b5069d44e2fbc4a9093d005b3ef0949add3dd27e -~~	() https://git.kernel.org/stable/c/b5069d44e2fbc4a9093d005b3ef0949add3dd27e - Patch
References	~~() https://git.kernel.org/stable/c/cc30042df6fcc82ea18acf0dace831503e60a0b7 -~~	() https://git.kernel.org/stable/c/cc30042df6fcc82ea18acf0dace831503e60a0b7 - Patch
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 5.5
CWE		CWE-401

21 Nov 2024, 06:35

Type	Values Removed	Values Added
Summary		(es) En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: hugetlb, userfaultfd: se corrige el error de restauración 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 código detectará que new_pagecache_page == false, y por lo tanto llamará 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() incrementará h->resv_hugepages causando una fuga 100% reproducible. Deberíamos tratar el caso is_continue de forma similar a agregar una página 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.
References	~~() https://git.kernel.org/stable/c/b5069d44e2fbc4a9093d005b3ef0949add3dd27e -~~	() https://git.kernel.org/stable/c/b5069d44e2fbc4a9093d005b3ef0949add3dd27e -
References	~~() https://git.kernel.org/stable/c/cc30042df6fcc82ea18acf0dace831503e60a0b7 -~~	() https://git.kernel.org/stable/c/cc30042df6fcc82ea18acf0dace831503e60a0b7 -

10 Apr 2024, 19:15

Type	Values Removed	Values Added
New CVE

Information

Published : 2024-04-10 19:15

Updated : 2025-03-27 21:05

NVD link : CVE-2021-47214

Mitre link : CVE-2021-47214

CVE.ORG link : CVE-2021-47214

JSON object : View

Products Affected

linux

linux_kernel

CWE

CWE-401

Missing Release of Memory after Effective Lifetime

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5.5 /10