misc: fastrpc: fix use-after-free of fastrpc_user in workqueue context_CVE-2026-53161

{
    "lastseen": "",
    "description": "In the Linux kernel, the following vulnerability has been resolved:\n\nmisc: fastrpc: fix use-after-free of fastrpc_user in workqueue context\n\nThere is a race between fastrpc_device_release() and the workqueue\nthat processes DSP responses. When the user closes the file descriptor,\nfastrpc_device_release() frees the fastrpc_user structure. Concurrently,\nan in-flight DSP invocation can complete and fastrpc_rpmsg_callback()\nschedules context cleanup via schedule_work(&ctx->put_work). If the\nworkqueue runs fastrpc_context_free() in parallel with or after\nfastrpc_device_release() has freed the user structure, it dereferences\nthe freed fastrpc_user. Depending on the state of the context at the\ntime of the race, any one of the following accesses can be hit:\n\n 1. fastrpc_buf_free() calls fastrpc_ipa_to_dma_addr(buf->fl->cctx, ...)\n    to strip the SID bits from the stored IOVA before passing the\n    physical address to dma_free_coherent().\n\n 2. fastrpc_free_map() reads map->fl->cctx->vmperms[0].vmid to\n    reconstruct the source permission bitmask needed for the\n    qcom_scm_assign_mem() call that returns memory from the DSP VM\n    back to HLOS.\n\n 3. fastrpc_free_map() acquires map->fl->lock to safely remove the\n    map node from the fl->maps list.\n\nThe resulting use-after-free manifests as:\n\n  pc : fastrpc_buf_free+0x38/0x80 [fastrpc]\n  lr : fastrpc_context_free+0xa8/0x1b0 [fastrpc]\n  fastrpc_context_free+0xa8/0x1b0 [fastrpc]\n  fastrpc_context_put_wq+0x78/0xa0 [fastrpc]\n  process_one_work+0x180/0x450\n  worker_thread+0x26c/0x388\n\nAdd kref-based reference counting to fastrpc_user. Have each invoke\ncontext take a reference on the user at allocation time and release it\nwhen the context is freed. Release the initial reference in\nfastrpc_device_release() at file close. Move the teardown of the user\nstructure \u2014 freeing pending contexts, maps, mmaps, and the channel\ncontext reference \u2014 into the kref release callback fastrpc_user_free(),\nso that it runs only when the last reference is dropped, regardless of\nwhether that happens at device close or after the final in-flight\ncontext completes.",
    "published": "2026-06-25T08:38:42.789Z",
    "modified": "2026-06-28T06:39:37.235Z",
    "type": "cve",
    "title": "misc: fastrpc: fix use-after-free of fastrpc_user in workqueue context",
    "source": "Linux",
    "references": "https://git.kernel.org/stable/c/c6e5c2be09f814377d7f1ce97370a5b7b3e02814\nhttps://git.kernel.org/stable/c/e1e3a05efe5954d5bad01157d79429d39a67a7ae\nhttps://git.kernel.org/stable/c/d42679eef34dd590b694ce3b666c5e2ba10cd4bf\nhttps://git.kernel.org/stable/c/df08fadcf0e5f3708365ec3b6d30b5aafd98bea1\nhttps://git.kernel.org/stable/c/ecea4967c2bff92c2fafbc59893f711b39f7b152\nhttps://git.kernel.org/stable/c/5278ccd357e0d7aeeb1e76c0f3e0e02894a9897c\nhttps://git.kernel.org/stable/c/fbe0947420eec18a84638d29468c2d563ce4e6a3\nhttps://git.kernel.org/stable/c/e85eb5feca8e254905ffa6c57a3c99c89a674a0f",
    "id": "CVE-2026-53161",
    "bulletinFamily": "",
    "cwe": null,
    "cvelist": null,
    "sourceData": "Linux Linux 6cffd79504ce040f460831030d3069fa1c99bb71\nLinux Linux 6cffd79504ce040f460831030d3069fa1c99bb71\nLinux Linux 6cffd79504ce040f460831030d3069fa1c99bb71\nLinux Linux 6cffd79504ce040f460831030d3069fa1c99bb71\nLinux Linux 6cffd79504ce040f460831030d3069fa1c99bb71\nLinux Linux 6cffd79504ce040f460831030d3069fa1c99bb71\nLinux Linux 6cffd79504ce040f460831030d3069fa1c99bb71\nLinux Linux 6cffd79504ce040f460831030d3069fa1c99bb71\nLinux Linux 5.1",
    "sourceHref": "",
    "cvss": {
        "score": 7.8,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
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        "baseScore": 0,
        "baseSeverity": "",
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        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
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    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Linux",
    "version": "6cffd79504ce040f460831030d3069fa1c99bb71",
    "vendor": "Linux",
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    "ai_score": 0
}