{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-31584", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-31584", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-04-24T14:42:13.586Z", "updatedAt": "2026-08-05T12:23:36.030Z", "importedAt": "2026-10-24T01:58:02.025Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "media: mediatek: vcodec: fix use-after-free in encoder release path", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nmedia: mediatek: vcodec: fix use-after-free in encoder release path\n\nThe fops_vcodec_release() function frees the context structure (ctx)\nwithout first cancelling any pending or running work in ctx->encode_work.\nThis creates a race window where the workqueue handler (mtk_venc_worker)\nmay still be accessing the context memory after it has been freed.\n\nRace condition:\n\n CPU 0 (release path) CPU 1 (workqueue)\n --------------------- ------------------\n fops_vcodec_release()\n v4l2_m2m_ctx_release()\n v4l2_m2m_cancel_job()\n // waits for m2m job \"done\"\n mtk_venc_worker()\n v4l2_m2m_job_finish()\n // m2m job \"done\"\n // BUT worker still running!\n // post-job_finish access:\n other ctx dereferences\n // UAF if ctx already freed\n // returns (job \"done\")\n kfree(ctx) // ctx freed\n\nRoot cause: The v4l2_m2m_ctx_release() only waits for the m2m job\nlifecycle (via TRANS_RUNNING flag), not the workqueue lifecycle.\nAfter v4l2_m2m_job_finish() is called, the m2m framework considers\nthe job complete and v4l2_m2m_ctx_release() returns, but the worker\nfunction continues executing and may still access ctx.\n\nThe work is queued during encode operations via:\n queue_work(ctx->dev->encode_workqueue, &ctx->encode_work)\nThe worker function accesses ctx->m2m_ctx, ctx->dev, and other ctx\nfields even after calling v4l2_m2m_job_finish().\n\nThis vulnerability was confirmed with KASAN by running an instrumented\ntest module that widens the post-job_finish race window. KASAN detected:\n\n BUG: KASAN: slab-use-after-free in mtk_venc_worker+0x159/0x180\n Read of size 4 at addr ffff88800326e000 by task kworker/u8:0/12\n\n Workqueue: mtk_vcodec_enc_wq mtk_venc_worker\n\n Allocated by task 47:\n __kasan_kmalloc+0x7f/0x90\n fops_vcodec_open+0x85/0x1a0\n\n Freed by task 47:\n __kasan_slab_free+0x43/0x70\n kfree+0xee/0x3a0\n fops_vcodec_release+0xb7/0x190\n\nFix this by calling cancel_work_sync(&ctx->encode_work) before kfree(ctx).\nThis ensures the workqueue handler is both cancelled (if pending) and\nsynchronized (waits for any running handler to complete) before the\ncontext is freed.\n\nPlacement rationale: The fix is placed after v4l2_ctrl_handler_free()\nand before list_del_init(&ctx->list). At this point, all m2m operations\nare done (v4l2_m2m_ctx_release() has returned), and we need to ensure\nthe workqueue is synchronized before removing ctx from the list and\nfreeing it.\n\nNote: The open error path does NOT need cancel_work_sync() because\nINIT_WORK() only initializes the work structure - it does not schedule\nit. Work is only scheduled later during device_run() operations.", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "0934d37596151edce115c6d0843a9ad7d5e5d232", "status": "affected", "versionType": "git", "lessThan": "9a9bdaf9dc42ccca50e53f82165292f74a365c11" }, { "version": "0934d37596151edce115c6d0843a9ad7d5e5d232", "status": "affected", "versionType": "git", "lessThan": "a8a55913552aed45108525d1851c65e1db0cc25b" }, { "version": "0934d37596151edce115c6d0843a9ad7d5e5d232", "status": "affected", "versionType": "git", "lessThan": "f99353cd0e9f58bf17889049137b8d65fb44ebf1" }, { "version": "0934d37596151edce115c6d0843a9ad7d5e5d232", "status": "affected", "versionType": "git", "lessThan": "93d9a58961a9e09306857e999b3ee76aa4be67f0" }, { "version": "0934d37596151edce115c6d0843a9ad7d5e5d232", "status": "affected", "versionType": "git", "lessThan": "f1692337c6fa26e04f89b22a4d84bf5b7ada50d1" }, { "version": "0934d37596151edce115c6d0843a9ad7d5e5d232", "status": "affected", "versionType": "git", "lessThan": "76e35091ffc722ba39b303e48bc5d08abb59dd56" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "6.6", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "6.6" }, { "version": "6.6.136", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.83", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.24", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "6.19.14", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.19.*" }, { "version": "7.0.1", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.0.*" }, { "version": "7.1", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }