CVE-2021-47221

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2021-47221
In the Linux kernel, the following vulnerability has been resolved: mm/slub: actually fix freelist pointer vs redzoning It turns out that SLUB redzoning ("slub_debug=Z") checks from s->object_size rather than from s->inuse (which is normally bumped to make room for the freelist pointer), so a cache created with an object size less than 24 would have the freelist pointer written beyond s->object_size, causing the redzone to be corrupted by the freelist pointer. This was very visible with "slub_debug=ZF": BUG test (Tainted: G B ): Right Redzone overwritten ----------------------------------------------------------------------------- INFO: 0xffff957ead1c05de-0xffff957ead1c05df @offset=1502. First byte 0x1a instead of 0xbb INFO: Slab 0xffffef3950b47000 objects=170 used=170 fp=0x0000000000000000 flags=0x8000000000000200 INFO: Object 0xffff957ead1c05d8 @offset=1496 fp=0xffff957ead1c0620 Redzone (____ptrval____): bb bb bb bb bb bb bb bb ........ Object (____ptrval____): 00 00 00 00 00 f6 f4 a5 ........ Redzone (____ptrval____): 40 1d e8 1a aa @.... Padding (____ptrval____): 00 00 00 00 00 00 00 00 ........ Adjust the offset to stay within s->object_size. (Note that no caches of in this size range are known to exist in the kernel currently.)

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/ce6e8bee7a3883e8008b30f5887dbb426aac6a35 Patch
https://git.kernel.org/stable/c/e41a49fadbc80b60b48d3c095d9e2ee7ef7c9a8e Patch
https://git.kernel.org/stable/c/f6ed2357541612a13a5841b3af4dc32ed984a25f Patch
https://git.kernel.org/stable/c/ce6e8bee7a3883e8008b30f5887dbb426aac6a35 Patch
https://git.kernel.org/stable/c/e41a49fadbc80b60b48d3c095d9e2ee7ef7c9a8e Patch
https://git.kernel.org/stable/c/f6ed2357541612a13a5841b3af4dc32ed984a25f 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:5.13:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.13:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.13:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.13:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.13:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.13:rc6:*:*:*:*:*:*
History

29 Apr 2025, 19:07

Type Values Removed Values Added
First Time Linux linux Kernel
Linux
References () https://git.kernel.org/stable/c/ce6e8bee7a3883e8008b30f5887dbb426aac6a35 - () https://git.kernel.org/stable/c/ce6e8bee7a3883e8008b30f5887dbb426aac6a35 - Patch
References () https://git.kernel.org/stable/c/e41a49fadbc80b60b48d3c095d9e2ee7ef7c9a8e - () https://git.kernel.org/stable/c/e41a49fadbc80b60b48d3c095d9e2ee7ef7c9a8e - Patch
References () https://git.kernel.org/stable/c/f6ed2357541612a13a5841b3af4dc32ed984a25f - () https://git.kernel.org/stable/c/f6ed2357541612a13a5841b3af4dc32ed984a25f - Patch
CVSS v2 : unknown
v3 : unknown 		v2 : unknown
v3 : 5.5
CPE cpe:2.3:o:linux:linux_kernel:5.13:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.13:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.13:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.13:rc6:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.13:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.13:rc3:*:*:*:*:*:*
CWE CWE-763

21 Nov 2024, 06:35

Type Values Removed Values Added
References () https://git.kernel.org/stable/c/ce6e8bee7a3883e8008b30f5887dbb426aac6a35 - () https://git.kernel.org/stable/c/ce6e8bee7a3883e8008b30f5887dbb426aac6a35 -
References () https://git.kernel.org/stable/c/e41a49fadbc80b60b48d3c095d9e2ee7ef7c9a8e - () https://git.kernel.org/stable/c/e41a49fadbc80b60b48d3c095d9e2ee7ef7c9a8e -
References () https://git.kernel.org/stable/c/f6ed2357541612a13a5841b3af4dc32ed984a25f - () https://git.kernel.org/stable/c/f6ed2357541612a13a5841b3af4dc32ed984a25f -
Summary
  • (es) En el kernel de Linux, se resolvió la siguiente vulnerabilidad: mm/slub: en realidad corrige el puntero de lista libre frente a redzoning. Resulta que SLUB redzoning ("slub_debug=Z") verifica desde s->object_size en lugar de s->inuse (que normalmente se elimina para dejar espacio para el puntero de lista libre), por lo que un caché creado con un tamaño de objeto menor a 24 tendría el puntero de lista libre escrito más allá de s->object_size, causando que el puntero de lista libre corrompa la zona roja. Esto fue muy visible con "slub_debug=ZF": prueba de BUG(contaminada: GB): zona roja derecha sobrescrita ---------------------------- ------------------------------------------------- INFORMACIÓN : 0xffff957ead1c05de-0xffff957ead1c05df @offset=1502. Primer byte 0x1a en lugar de 0xbb INFORMACIÓN: slab 0xffffef3950b47000 objetos=170 usados=170 fp=0x0000000000000000 banderas=0x80000000000000200 INFORMACIÓN: Objeto 0xffff957ead1c05d8 @offset=1496 fp=0xffff9 57ead1c0620 Zona roja (____ptrval____): bb bb bb bb bb bb bb bb .... .... Objeto (____ptrval____): 00 00 00 00 00 f6 f4 a5 ........ Redzone (____ptrval____): 40 1d e8 1a aa @.... Relleno (____ptrval____): 00 00 00 00 00 00 00 00 ........ Ajuste el desplazamiento para permanecer dentro de s->object_size. (Tenga en cuenta que actualmente no se sabe que existan cachés de este rango de tamaño en el kernel).

21 May 2024, 15:15

Type Values Removed Values Added
New CVE
Information

Published : 2024-05-21 15:15

Updated : 2025-04-29 19:07

NVD link : CVE-2021-47221

Mitre link : CVE-2021-47221

CVE.ORG link : CVE-2021-47221

JSON object : View

Products Affected

linux

  • linux_kernel
CWE
CWE-763

Release of Invalid Pointer or Reference