{"id":"CVE-2026-53161","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-53161","generatedAt":"2026-10-28T07:04:06.271Z","title":"In the Linux kernel, the following vulnerability has been resolved: misc: fastrpc: fix use-after-free of fastrpc_user in workqueue context There is a race between fastrpc_device_release() and the workqueue that processes DSP responses.","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 — freeing pending contexts, maps, mmaps, and the channel\ncontext reference — 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":"2026-06-25T09:16:33.000Z","lastModified":"2026-07-06T16:42:03.000Z","status":"Analyzed","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","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"},"cwe":["CWE-416"],"affected":["linux/linux kernel"],"epss":{"score":0.00126,"percentile":0.02237,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.13%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/5278ccd357e0d7aeeb1e76c0f3e0e02894a9897c","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c6e5c2be09f814377d7f1ce97370a5b7b3e02814","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d42679eef34dd590b694ce3b666c5e2ba10cd4bf","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/df08fadcf0e5f3708365ec3b6d30b5aafd98bea1","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e1e3a05efe5954d5bad01157d79429d39a67a7ae","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e85eb5feca8e254905ffa6c57a3c99c89a674a0f","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ecea4967c2bff92c2fafbc59893f711b39f7b152","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/fbe0947420eec18a84638d29468c2d563ce4e6a3","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-53161","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}