Bug 2309804 (CVE-2024-44973)

Summary: CVE-2024-44973 kernel: mm, slub: do not call do_slab_free for kfence object
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: dfreiber, drow, hwilbert048, jburrell, vkumar
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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Bug Depends On: 2309812    
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Description OSIDB Bzimport 2024-09-04 19:21:33 UTC 
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.
Comment 1 Robb Gatica 2024-09-04 20:03:44 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024090425-CVE-2024-44973-a92d@gregkh/T
Comment 2 Ervin Graves 2024-10-31 15:19:23 UTC Comment hidden (spam)