{ "schema_version": "1.6.1", "id": "RPI-CVE-2025-21726", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2025-21726" ], "published": "2025-02-27T02:06:37Z", "summary": "padata: avoid UAF for reorder_work", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\npadata: avoid UAF for reorder_work\n\nAlthough the previous patch can avoid ps and ps UAF for _do_serial, it\ncan not avoid potential UAF issue for reorder_work. This issue can\nhappen just as below:\n\ncrypto_request\t\t\tcrypto_request\t\tcrypto_del_alg\npadata_do_serial\n ...\n padata_reorder\n // processes all remaining\n // requests then breaks\n while (1) {\n if (!padata)\n break;\n ...\n }\n\n\t\t\t\tpadata_do_serial\n\t\t\t\t // new request added\n\t\t\t\t list_add\n // sees the new request\n queue_work(reorder_work)\n\t\t\t\t padata_reorder\n\t\t\t\t queue_work_on(squeue->work)\n...\n\n\t\t\t\t\n\t\t\t\tpadata_serial_worker\n\t\t\t\t// completes new request,\n\t\t\t\t// no more outstanding\n\t\t\t\t// requests\n\n\t\t\t\t\t\t\tcrypto_del_alg\n\t\t\t\t\t\t\t // free pd\n\n\ninvoke_padata_reorder\n // UAF of pd\n\nTo avoid UAF for 'reorder_work', get 'pd' ref before put 'reorder_work'\ninto the 'serial_wq' and put 'pd' ref until the 'serial_wq' finish.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.1.47-1+rpt4" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.1.0-rpi3-rpi-2712", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v6", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v8", "binary_version": "1:6.1.47-1+rpt4" } ] }, "database_specific": { "per_version": { "1:6.1.47-1+rpt4": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.129", "compiled_filter": false } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2025-21726" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/f4f1b1169fc3694f9bc3e28c6c68dbbf4cc744c0" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/4c6209efea2208597dbd3e52dc87a0d1a8f2dbe1" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/7000507bb0d2ceb545c0a690e0c707c897d102c2" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/6f45ef616775b0ce7889b0f6077fc8d681ab30bc" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/8ca38d0ca8c3d30dd18d311f1a7ec5cb56972cac" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/a54091c24220a4cd847d5b4f36d678edacddbaf0" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/dd7d37ccf6b11f3d95e797ebe4e9e886d0332600" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-05T12:19:11Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.8, "cvss_v3_severity": "High", "scenario": "AV:L - The vulnerable padata reorder machinery is driven through pcrypt, reached locally via AF_ALG (`algif_aead`) socket operations or local xfrm/IPsec setup, and the `pd` free is triggered by local crypto-netlink/CPU-hotplug activity. No remote peer can reach or free the `parallel_data` object, so the attack requires local system access.\nAC:L - The attacker controls both sides of the race \u2014 they submit an unbounded stream of concurrent pcrypt AEAD requests to keep `reorder_work` queued while simultaneously driving the shell/pd teardown, and `serial_wq` is allocated with `max_active=1`, so `reorder_work` is routinely stalled behind serial workers, widening the window. Repeated attempts in a tight loop make the race reliably winnable, as the LTP `pcrypt_aead01` reproducer for the sibling bug demonstrates.\nPR:L - An unprivileged local user can fully drive the parallel/serial request side with no capability check at all via `AF_ALG` `algif_aead` binding `pcrypt(rfc4106(gcm(aes)))`, and the pd-release side is reachable through `padata_replace()` on CPU hotplug (suspend/resume, which logind grants to active unprivileged sessions) as well as through crypto netlink. No root-only gate is required on the path that actually corrupts memory.\nUI:N - The attacker issues both the crypto requests and the teardown that frees `parallel_data` themselves; no victim must mount a filesystem, open a file, or take any other action.\nS:U - The use-after-free corrupts kernel heap memory and is exploited within the same kernel security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - After `pd` is freed and reclaimed by sprayed attacker data, `padata_reorder()` follows `pd->ps->pinst`, `pd->reorder_list`, `pd->squeue` and `pd->cpumask.pcpu` out of the freed object, giving an attacker-directed read primitive over arbitrary kernel memory and disclosure of kernel state.\nI:H - The same freed object yields write primitives \u2014 `spin_trylock_bh(&pd->lock)`, `refcount_inc(&pd->refcnt)`, `++pd->processed`, and especially `list_del_init()`/`list_add_tail()` through attacker-controlled `reorder_list`/`squeue` pointers, plus a controlled `workqueue_struct *` fed to `queue_work_on()` \u2014 which is exploitable for arbitrary write and control-flow hijack leading to privilege escalation.\nA:H - Even without successful heap grooming, dereferencing the freed `parallel_data` reliably produces a KASAN slab-use-after-free splat, spinlock corruption, and kernel oops/panic, taking the whole system down; the crash can be reproduced repeatedly." } } }