{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2024-38663","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2024-06-21T11:16:40.592Z","datePublished":"2024-06-24T13:50:51.710Z","dateUpdated":"2026-08-05T11:33:20.039Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T11:33:20.039Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: fix list corruption from resetting io stat\n\nSince commit 3b8cc6298724 (\"blk-cgroup: Optimize blkcg_rstat_flush()\"),\neach iostat instance is added to blkcg percpu list, so blkcg_reset_stats()\ncan't reset the stat instance by memset(), otherwise the llist may be\ncorrupted.\n\nFix the issue by only resetting the counter part."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerability is triggered by writing to the cgroup v1 control file `blkio.reset_stats` and by submitting block I/O from the same cgroup, both of which require local access to the machine (cgroupfs write + write(2)/read(2) to a block device or file). There is no network, adjacent-network, or physical path into `blkcg_reset_stats()`.\nAC:L - The attacker controls both sides of the race: they generate I/O inside their own cgroup to populate `blkcg->lhead` via `blk_cgroup_bio_start()` and concurrently write `blkio.reset_stats` in a loop from another thread, and `blkcg_reset_stats()` takes only `blkcg->lock`, which the I/O path never acquires. Once `lqueued` is cleared on a still-linked node, the very next bio deterministically re-adds it and forms a cycle — no memory layout or timing outside the attacker's influence is needed, and failed attempts can be retried indefinitely.\nPR:L - `cgroup_kn_set_ugid()` explicitly sets cgroup directories and control files to the uid/gid of their creator, so an unprivileged user or container root with write access to a delegated cgroup v1 blkio subtree (standard in LXC/LXD, Docker/Kubernetes, and systemd `Delegate=` setups) can `mkdir` a child cgroup and own its `blkio.reset_stats` file, then generate I/O and write it. No init-namespace root or capability is required, and the resulting lockless-list corruption is not confined to the attacker's own cgroup — it hangs the whole machine.\nUI:N - The attacker performs both the I/O submission and the `blkio.reset_stats` write from their own processes; no victim has to mount, open, or otherwise interact with anything.\nS:U - The corrupted `blkg_iostat_set` lockless lists and the resulting crash/corruption are entirely within the kernel's own security authority; no VM, hypervisor, or IOMMU boundary is crossed by the bug itself.\nC:H - This is a memory-corruption defect — `memset()` over live `llist_node` linkage and the `lqueued` membership flag inside per-CPU `blkg_iostat_set` objects — which desynchronizes the list-membership invariant that the blkg lifetime rules depend on (in the v6.2–v6.4 part of the affected range llist membership held a `percpu_ref` on `blkg->refcnt`, so lost/duplicated puts corrupt `struct blkcg_gq` lifetime accounting). The same broken invariant in this exact function has since produced a confirmed slab use-after-free in `__blkcg_rstat_flush()`, and dangling/looped links into kmalloc'd blkg and per-CPU stat memory are leverageable for kernel memory disclosure via heap grooming.\nI:H - The corrupted links cause `__blkcg_rstat_flush()` to write unbounded, attacker-influenced counter deltas through the cyclic chain into ancestor blkgs' `iostat` (`blkcg_iostat_update(parent, ...)`), modifying kernel state belonging to higher-privileged cgroups, and the underlying pointer/refcount corruption of `struct blkcg_gq` is the classic primitive for heap grooming and writes through stale pointers. Per kernel CNA practice, list corruption of this class is treated as exploitable for control-flow-relevant memory modification.\nA:H - The reliable, immediate outcome is a cyclic lockless list that makes `llist_for_each_entry_safe()` in `__blkcg_rstat_flush()` spin forever while holding the global `raw_spinlock_t blkg_stat_lock` with local IRQs disabled — every other CPU entering rstat flush then spins too, producing a hard lockup and watchdog panic. Additionally, the `memset`-to-`bis->blkg = blkg` window lets a concurrent flush dereference a NULL `blkg`, and the truncated chains permanently leak blkg references and per-CPU stats."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["block/blk-cgroup.c"],"versions":[{"version":"3b8cc6298724021da845f2f9fd7dd4b6829a6817","lessThan":"d4a60298ac34f027a09f8f893fdbd9e06279bb24","status":"affected","versionType":"git"},{"version":"3b8cc6298724021da845f2f9fd7dd4b6829a6817","lessThan":"89bb36c72e1951843f9e04dc84412e31fcc849a9","status":"affected","versionType":"git"},{"version":"3b8cc6298724021da845f2f9fd7dd4b6829a6817","lessThan":"6da6680632792709cecf2b006f2fe3ca7857e791","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["block/blk-cgroup.c"],"versions":[{"version":"6.2","status":"affected"},{"version":"0","lessThan":"6.2","status":"unaffected","versionType":"semver"},{"version":"6.6.33","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.9.4","lessThanOrEqual":"6.9.*","status":"unaffected","versionType":"semver"},{"version":"6.10","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.6.33"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.9.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.10"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/d4a60298ac34f027a09f8f893fdbd9e06279bb24"},{"url":"https://git.kernel.org/stable/c/89bb36c72e1951843f9e04dc84412e31fcc849a9"},{"url":"https://git.kernel.org/stable/c/6da6680632792709cecf2b006f2fe3ca7857e791"}],"title":"blk-cgroup: fix list corruption from resetting io stat","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2024-06-25T13:51:20.493125Z","id":"CVE-2024-38663","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2024-06-25T13:51:34.429Z"}},{"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2024-08-02T04:12:26.031Z"},"title":"CVE Program Container","references":[{"url":"https://git.kernel.org/stable/c/d4a60298ac34f027a09f8f893fdbd9e06279bb24","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/89bb36c72e1951843f9e04dc84412e31fcc849a9","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/6da6680632792709cecf2b006f2fe3ca7857e791","tags":["x_transferred"]}]}]}}