CVE-2021-47221

Advisory lineage Upstream: 0 Downstream: 3
Analyzed
Published: 21 May 2024, 14:19
Last modified:11 May 2026, 13:50

Vulnerability Summary

Overall Risk (default)
low
22/100
CVSS Score
5.5 MEDIUM
v3.1 (nvd)
EPSS Score
0.02% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

21 May 2024, 14:19
Published
Vulnerability first disclosed
11 May 2026, 13:50
Last Modified
Vulnerability information updated

Description

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.)

CVSS Metrics

  • v3.1•MEDIUM•Score: 5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Trends

Current EPSS score: 0.02%• Percentile: 6%

Techniques & Countermeasures

  • CWE-763•Release of Invalid Pointer or Reference

    The product attempts to return a memory resource to the system, but it calls the wrong release function or calls the appropriate release function incorrectly.

Affected Systems

  • linux•linux

    ≥ 89b83f282d8ba380cf2124f88106c57df49c538c, < f6ed2357541612a13a5841b3af4dc32ed984a25f | ≥ 89b83f282d8ba380cf2124f88106c57df49c538c, < ce6e8bee7a3883e8008b30f5887dbb426aac6a35 | ≥ 89b83f282d8ba380cf2124f88106c57df49c538c, < e41a49fadbc80b60b48d3c095d9e2ee7ef7c9a8e | 5.7

  • linux•linux_kernel

    ≥ 5.7, < 5.10.46 | ≥ 5.11, < 5.12.13 | 5.13:rc1 | 5.13:rc2 | 5.13:rc3 | 5.13:rc4 | 5.13:rc5 | 5.13:rc6

References (3)