{ "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" ] } ] } ] } }