CVE-2024-56709 (GCVE-0-2024-56709)
Vulnerability from cvelistv5
Published
2024-12-29 08:42
Modified
2026-08-05 11:46
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: io_uring: check if iowq is killed before queuing task work can be executed after the task has gone through io_uring termination, whether it's the final task_work run or the fallback path. In this case, task work will find ->io_wq being already killed and null'ed, which is a problem if it then tries to forward the request to io_queue_iowq(). Make io_queue_iowq() fail requests in this case. Note that it also checks PF_KTHREAD, because the user can first close a DEFER_TASKRUN ring and shortly after kill the task, in which case ->iowq check would race.
References
Impacted products
Vendor Product Version
Linux Linux Version: 773af69121ecc6c53d192661af8d53bb3db028ae
Version: 773af69121ecc6c53d192661af8d53bb3db028ae
Version: 773af69121ecc6c53d192661af8d53bb3db028ae
Version: 773af69121ecc6c53d192661af8d53bb3db028ae
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring: check if iowq is killed before queuing\n\ntask work can be executed after the task has gone through io_uring\ntermination, whether it\u0027s the final task_work run or the fallback path.\nIn this case, task work will find -\u003eio_wq being already killed and\nnull\u0027ed, which is a problem if it then tries to forward the request to\nio_queue_iowq(). Make io_queue_iowq() fail requests in this case.\n\nNote that it also checks PF_KTHREAD, because the user can first close\na DEFER_TASKRUN ring and shortly after kill the task, in which case\n-\u003eiowq check would race."
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            "baseSeverity": "HIGH",
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              "value": "AV:L - The vulnerability is reached purely through the io_uring syscall interface (io_uring_setup/io_uring_enter, SQE submission, and close(2) of the ring fd), which requires local access to the machine. Per kernel scoring guidance io_uring bugs are Local.\nAC:L - The attacker controls both sides of the race \u2014 they choose exactly when to close the DEFER_TASKRUN ring (driving the request into the PF_KTHREAD fallback worker) and when to exit the submitting task (driving io_wq_put_and_exit/kfree), and can retry the whole sequence in a fresh process arbitrarily many times. The NULL-io_wq/BUG_ON variant is essentially deterministic once the exit ordering is arranged.\nPR:L - Any unprivileged local user with default io_uring access can create the ring, submit an IOSQE_ASYNC/IOSQE_IO_DRAIN request (REQ_F_FORCE_ASYNC), and trigger the exit race; no capabilities, root, or user-namespace tricks are required.\nUI:N - The entire sequence is performed by the attacker\u0027s own process and threads with no victim action of any kind.\nS:U - The corruption and its consequences are confined to the Linux kernel\u0027s own security authority; there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - The freed struct io_wq is read back after kfree (wq-\u003estate, wq-\u003eacct[], wq-\u003efree_list, wq-\u003etask, wq-\u003edo_work/free_work), so an attacker who reclaims the kmalloc-1k slot obtains a use-after-free read primitive over kernel heap contents, and per guidance a UAF is scored High.\nI:H - io_run_cancel() invokes wq-\u003edo_work(work) and wq-\u003efree_work(work) \u2014 indirect calls through function pointers read from the freed, attacker-reclaimable allocation \u2014 and io_wq_insert_work() writes list pointers into that freed memory, giving control-flow hijack and write primitives suitable for privilege escalation.\nA:H - The NULL-io_wq path hits BUG_ON() for a guaranteed kernel oops (full panic with panic_on_oops), and because it fires inside io_fallback_req_func() while holding ctx-\u003euring_lock the mutex is leaked, permanently hanging io_ring_exit_work and any task touching that ring; the UAF variant additionally crashes on freed memory."
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    "datePublished": "2024-12-29T08:42:58.403Z",
    "dateReserved": "2024-12-27T15:00:39.857Z",
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