发布于3月6日3月6日 Members Debian: CVE-2021-47221: linux -- security update Severity 4 CVSS (AV:L/AC:M/Au:N/C:P/I:P/A:P) Published 05/21/2024 Created 07/31/2024 Added 07/30/2024 Modified 07/30/2024 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: GB): 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.) Solution(s) debian-upgrade-linux References https://attackerkb.com/topics/cve-2021-47221 CVE - 2021-47221
