{"id":"CVE-2024-44973","state":"PUBLISHED","title":"mm, slub: do not call do_slab_free for kfence object","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm, slub: do not call do_slab_free for kfence object\n\nIn 782f8906f805 the freeing of kfence objects was moved from deep\ninside do_slab_free to the wrapper functions outside. This is a nice\nchange, but unfortunately it missed one spot in __kmem_cache_free_bulk.\n\nThis results in a crash like this:\n\nBUG skbuff_head_cache (Tainted: G S  B       E     ): Padding overwritten. 0xffff88907fea0f00-0xffff88907fea0fff @offset=3840\n\nslab_err (mm/slub.c:1129)\nfree_to_partial_list (mm/slub.c:? mm/slub.c:4036)\nslab_pad_check (mm/slub.c:864 mm/slub.c:1290)\ncheck_slab (mm/slub.c:?)\nfree_to_partial_list (mm/slub.c:3171 mm/slub.c:4036)\nkmem_cache_alloc_bulk (mm/slub.c:? mm/slub.c:4495 mm/slub.c:4586 mm/slub.c:4635)\nnapi_build_skb (net/core/skbuff.c:348 net/core/skbuff.c:527 net/core/skbuff.c:549)\n\nAll the other callers to do_slab_free appear to be ok.\n\nAdd a kfence_free check in __kmem_cache_free_bulk to avoid the crash.","publishedAt":"2024-09-04T19:00:23.444Z","updatedAt":"2026-08-05T11:37:23.425Z","severity":{"score":8.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"782f8906f8057efc7151b4b98b0a0280a71d005f","status":"affected","lessThan":"b35cd7f1e969aaa63e6716d82480f6b8a3230949","versionType":"git"},{"version":"782f8906f8057efc7151b4b98b0a0280a71d005f","status":"affected","lessThan":"a371d558e6f3aed977a8a7346350557de5d25190","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/slub.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.8","versionType":"semver"},{"version":"6.10.5","status":"unaffected","lessThanOrEqual":"6.10.*","versionType":"semver"},{"version":"6.11","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/slub.c"]}],"references":["https://git.kernel.org/stable/c/b35cd7f1e969aaa63e6716d82480f6b8a3230949","https://git.kernel.org/stable/c/a371d558e6f3aed977a8a7346350557de5d25190"],"weaknesses":[],"ingestedAt":"2026-10-29T20:07:47.831Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2024/44xxx/CVE-2024-44973.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2024-44973","state":"PUBLISHED","datePublished":"2024-09-04T19:00:23.444Z","dateUpdated":"2026-08-05T11:37:23.425Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-08-21T05:34:56.669Z"},"containers":{"cna":{"title":"mm, slub: do not call do_slab_free for kfence object","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm, slub: do not call do_slab_free for kfence object\n\nIn 782f8906f805 the freeing of kfence objects was moved from deep\ninside do_slab_free to the wrapper functions outside. This is a nice\nchange, but unfortunately it missed one spot in __kmem_cache_free_bulk.\n\nThis results in a crash like this:\n\nBUG skbuff_head_cache (Tainted: G S  B       E     ): Padding overwritten. 0xffff88907fea0f00-0xffff88907fea0fff @offset=3840\n\nslab_err (mm/slub.c:1129)\nfree_to_partial_list (mm/slub.c:? mm/slub.c:4036)\nslab_pad_check (mm/slub.c:864 mm/slub.c:1290)\ncheck_slab (mm/slub.c:?)\nfree_to_partial_list (mm/slub.c:3171 mm/slub.c:4036)\nkmem_cache_alloc_bulk (mm/slub.c:? mm/slub.c:4495 mm/slub.c:4586 mm/slub.c:4635)\nnapi_build_skb (net/core/skbuff.c:348 net/core/skbuff.c:527 net/core/skbuff.c:549)\n\nAll the other callers to do_slab_free appear to be ok.\n\nAdd a kfence_free check in __kmem_cache_free_bulk to avoid the crash."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"782f8906f8057efc7151b4b98b0a0280a71d005f","status":"affected","lessThan":"b35cd7f1e969aaa63e6716d82480f6b8a3230949","versionType":"git"},{"version":"782f8906f8057efc7151b4b98b0a0280a71d005f","status":"affected","lessThan":"a371d558e6f3aed977a8a7346350557de5d25190","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/slub.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.8","versionType":"semver"},{"version":"6.10.5","status":"unaffected","lessThanOrEqual":"6.10.*","versionType":"semver"},{"version":"6.11","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/slub.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/b35cd7f1e969aaa63e6716d82480f6b8a3230949"},{"url":"https://git.kernel.org/stable/c/a371d558e6f3aed977a8a7346350557de5d25190"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":8.1,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The primary and reported trigger is the NIC receive softirq path — `napi_build_skb()` → `napi_skb_cache_get()` → `kmem_cache_alloc_bulk(skbuff_cache, GFP_ATOMIC, …)` — driven entirely by inbound packets, with the same remote traffic flood supplying the GFP_ATOMIC pressure that makes the bulk allocation fail mid-array. No local access is needed to reach the vulnerable free path.\nAC:H - Exploitation requires KFENCE to be active with a non-zero sample interval, the timer-driven `kfence_allocation_gate` (~10 allocations/second system-wide) to land on one of the attacker's bulk-allocation slots, and that same bulk allocation to then fail at a later index — the KFENCE sampling gate is a periodic timer the attacker cannot influence, so the required coincidence is beyond attacker control.\nPR:N - The network receive path is reached by any packet arriving on a NIC using `napi_build_skb()`/`napi_alloc_skb()`, with no authentication, credentials, or local account required.\nUI:N - The bulk skb allocation path runs autonomously in softirq context on packet receipt; no victim action of any kind is needed.\nS:U - The corruption is confined to the kernel's own slab allocator metadata and heap; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - A KFENCE pool page is inserted into a live cache's partial list, so SLUB subsequently hands out memory aliasing other subsystems' live KFENCE-guarded objects, and free hooks read `obj_exts[]` out of bounds into static kernel data — both allow disclosure of arbitrary kernel memory contents.\nI:H - `set_freepointer()` writes past the KFENCE object into the redzone/guard page, `slab->inuse` underflows to 65535, and the aliased pool page lets the allocator return the same memory to two owners, plus out-of-bounds `obj_exts[]` writes into `kfence_metadata_init[]` — a full heap corruption primitive suitable for control-flow hijacking.\nA:H - The reported real-world effect is a slab corruption BUG (`Padding overwritten` / `check_slab`) and kernel crash; without debug enabled, allocations served from unmapped KFENCE guard pages and the NULL `slab_cache` on the injected page cause oopses and panics."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T11:37:23.425Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"6.10.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"6.11"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2024-44973","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2024-09-10T17:39:02.040290Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2024-09-12T17:33:34.160Z"}}]}}}