CVE-2024-44973: mm, slub: do not call do_slab_free for kfence object

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-09-04 · updated 2026-08-04

Description

In the Linux kernel, the following vulnerability has been resolved: mm, slub: do not call do_slab_free for kfence object In 782f8906f805 the freeing of kfence objects was moved from deep inside do_slab_free to the wrapper functions outside. This is a nice change, but unfortunately it missed one spot in __kmem_cache_free_bulk. This results in a crash like this: BUG skbuff_head_cache (Tainted: G S B E ): Padding overwritten. 0xffff88907fea0f00-0xffff88907fea0fff @offset=3840 slab_err (mm/slub.c:1129) free_to_partial_list (mm/slub.c:? mm/slub.c:4036) slab_pad_check (mm/slub.c:864 mm/slub.c:1290) check_slab (mm/slub.c:?) free_to_partial_list (mm/slub.c:3171 mm/slub.c:4036) kmem_cache_alloc_bulk (mm/slub.c:? mm/slub.c:4495 mm/slub.c:4586 mm/slub.c:4635) napi_build_skb (net/core/skbuff.c:348 net/core/skbuff.c:527 net/core/skbuff.c:549) All the other callers to do_slab_free appear to be ok. Add a kfence_free check in __kmem_cache_free_bulk to avoid the crash.

Affected products

Linux kernel: from 6.8 before 6.10.5; 6.11-rc1, 6.11-rc2 — fixed in 6.10.5

How to fix

Upgrade to a fixed version: Linux kernel 6.10.5. Check the vendor advisory for mitigations.

References

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