{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-41045", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-07-12T12:17:45.624Z", "datePublished": "2024-07-29T14:32:02.866Z", "dateUpdated": "2026-08-05T11:34:57.115Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:34:57.115Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Defer work in bpf_timer_cancel_and_free\n\nCurrently, the same case as previous patch (two timer callbacks trying\nto cancel each other) can be invoked through bpf_map_update_elem as\nwell, or more precisely, freeing map elements containing timers. Since\nthis relies on hrtimer_cancel as well, it is prone to the same deadlock\nsituation as the previous patch.\n\nIt would be sufficient to use hrtimer_try_to_cancel to fix this problem,\nas the timer cannot be enqueued after async_cancel_and_free. Once\nasync_cancel_and_free has been done, the timer must be reinitialized\nbefore it can be armed again. The callback running in parallel trying to\narm the timer will fail, and freeing bpf_hrtimer without waiting is\nsufficient (given kfree_rcu), and bpf_timer_cb will return\nHRTIMER_NORESTART, preventing the timer from being rearmed again.\n\nHowever, there exists a UAF scenario where the callback arms the timer\nbefore entering this function, such that if cancellation fails (due to\ntimer callback invoking this routine, or the target timer callback\nrunning concurrently). In such a case, if the timer expiration is\nsignificantly far in the future, the RCU grace period expiration\nhappening before it will free the bpf_hrtimer state and along with it\nthe struct hrtimer, that is enqueued.\n\nHence, it is clear cancellation needs to occur after\nasync_cancel_and_free, and yet it cannot be done inline due to deadlock\nissues. We thus modify bpf_timer_cancel_and_free to defer work to the\nglobal workqueue, adding a work_struct alongside rcu_head (both used at\n_different_ points of time, so can share space).\n\nUpdate existing code comments to reflect the new state of affairs." } ], "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 reached by loading and running an attacker-authored BPF program via the bpf() syscall, which requires local access to the system. BPF is explicitly classified as a local attack vector in kernel scoring guidance.\nAC:L - The UAF is deterministic and fully attacker-scripted: the BPF callback arms its own timer with a far-future expiry and then deletes its own map element, guaranteeing the freed-while-enqueued hrtimer; no race the attacker cannot control is involved, and the deadlock variant is likewise attacker-orchestrated across two CPUs.\nPR:L - The bpf_timer_* helpers are gated by bpf_token_capable(CAP_BPF), which resolves to ns_capable() in a BPF-token user namespace, so an unprivileged user with a delegated bpffs token (common in container environments) can reach it. This matches established scoring for BPF verifier/helper CVEs.\nUI:N - The attacker loads and triggers the BPF timer entirely on their own; no victim action of any kind is needed.\nS:U - The freed object and the corrupted hrtimer state are both kernel-internal; the impact stays within the kernel's own security authority with no crossing into a hypervisor or IOMMU boundary.\nC:H - The freed bpf_hrtimer remains linked in the per-CPU hrtimer rbtree, so the timer subsystem keeps reading from reallocated heap memory, and controlling the freed slot gives an attacker a reliable kernel-memory read primitive enabling arbitrary disclosure.\nI:H - Enqueue/rebalance operations write rb_node and expiry fields into the freed object, and __run_hrtimer() calls a function pointer fetched from that freed memory, yielding both arbitrary write and control-flow hijack primitives after a heap spray.\nA:H - Both defects reliably take down the machine — the UAF corrupts the per-CPU hrtimer queue causing panics, and the mutual hrtimer_cancel() deadlock between two timer callbacks wedges CPUs in softirq context permanently." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/bpf/helpers.c" ], "versions": [ { "version": "b00628b1c7d595ae5b544e059c27b1f5828314b4", "lessThan": "7aa5a19279c3639ae8b758b63f05d0c616a39fa1", "status": "affected", "versionType": "git" }, { "version": "b00628b1c7d595ae5b544e059c27b1f5828314b4", "lessThan": "a6fcd19d7eac1335eb76bc16b6a66b7f574d1d69", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/bpf/helpers.c" ], "versions": [ { "version": "5.15", "status": "affected" }, { "version": "0", "lessThan": "5.15", "status": "unaffected", "versionType": "semver" }, { "version": "6.9.10", "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": "5.15", "versionEndExcluding": "6.9.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.10" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/7aa5a19279c3639ae8b758b63f05d0c616a39fa1" }, { "url": "https://git.kernel.org/stable/c/a6fcd19d7eac1335eb76bc16b6a66b7f574d1d69" } ], "title": "bpf: Defer work in bpf_timer_cancel_and_free", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-02T04:46:51.645Z" }, "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/7aa5a19279c3639ae8b758b63f05d0c616a39fa1", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/a6fcd19d7eac1335eb76bc16b6a66b7f574d1d69", "tags": [ "x_transferred" ] } ] }, { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2024-41045", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-09-10T16:23:00.726132Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-09-11T17:34:02.451Z" } } ] } }