CVE-2026-31584 (GCVE-0-2026-31584)

Vulnerability from cvelistv5 – Published: 2026-04-24 14:42 – Updated: 2026-06-14 17:42
VLAI
Title
media: mediatek: vcodec: fix use-after-free in encoder release path
Summary
In the Linux kernel, the following vulnerability has been resolved: media: mediatek: vcodec: fix use-after-free in encoder release path The fops_vcodec_release() function frees the context structure (ctx) without first cancelling any pending or running work in ctx->encode_work. This creates a race window where the workqueue handler (mtk_venc_worker) may still be accessing the context memory after it has been freed. Race condition: CPU 0 (release path) CPU 1 (workqueue) --------------------- ------------------ fops_vcodec_release() v4l2_m2m_ctx_release() v4l2_m2m_cancel_job() // waits for m2m job "done" mtk_venc_worker() v4l2_m2m_job_finish() // m2m job "done" // BUT worker still running! // post-job_finish access: other ctx dereferences // UAF if ctx already freed // returns (job "done") kfree(ctx) // ctx freed Root cause: The v4l2_m2m_ctx_release() only waits for the m2m job lifecycle (via TRANS_RUNNING flag), not the workqueue lifecycle. After v4l2_m2m_job_finish() is called, the m2m framework considers the job complete and v4l2_m2m_ctx_release() returns, but the worker function continues executing and may still access ctx. The work is queued during encode operations via: queue_work(ctx->dev->encode_workqueue, &ctx->encode_work) The worker function accesses ctx->m2m_ctx, ctx->dev, and other ctx fields even after calling v4l2_m2m_job_finish(). This vulnerability was confirmed with KASAN by running an instrumented test module that widens the post-job_finish race window. KASAN detected: BUG: KASAN: slab-use-after-free in mtk_venc_worker+0x159/0x180 Read of size 4 at addr ffff88800326e000 by task kworker/u8:0/12 Workqueue: mtk_vcodec_enc_wq mtk_venc_worker Allocated by task 47: __kasan_kmalloc+0x7f/0x90 fops_vcodec_open+0x85/0x1a0 Freed by task 47: __kasan_slab_free+0x43/0x70 kfree+0xee/0x3a0 fops_vcodec_release+0xb7/0x190 Fix this by calling cancel_work_sync(&ctx->encode_work) before kfree(ctx). This ensures the workqueue handler is both cancelled (if pending) and synchronized (waits for any running handler to complete) before the context is freed. Placement rationale: The fix is placed after v4l2_ctrl_handler_free() and before list_del_init(&ctx->list). At this point, all m2m operations are done (v4l2_m2m_ctx_release() has returned), and we need to ensure the workqueue is synchronized before removing ctx from the list and freeing it. Note: The open error path does NOT need cancel_work_sync() because INIT_WORK() only initializes the work structure - it does not schedule it. Work is only scheduled later during device_run() operations.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 0934d37596151edce115c6d0843a9ad7d5e5d232 , < 9a9bdaf9dc42ccca50e53f82165292f74a365c11 (git)
Affected: 0934d37596151edce115c6d0843a9ad7d5e5d232 , < a8a55913552aed45108525d1851c65e1db0cc25b (git)
Affected: 0934d37596151edce115c6d0843a9ad7d5e5d232 , < f99353cd0e9f58bf17889049137b8d65fb44ebf1 (git)
Affected: 0934d37596151edce115c6d0843a9ad7d5e5d232 , < 93d9a58961a9e09306857e999b3ee76aa4be67f0 (git)
Affected: 0934d37596151edce115c6d0843a9ad7d5e5d232 , < f1692337c6fa26e04f89b22a4d84bf5b7ada50d1 (git)
Affected: 0934d37596151edce115c6d0843a9ad7d5e5d232 , < 76e35091ffc722ba39b303e48bc5d08abb59dd56 (git)
Create a notification for this product.
Linux Linux Affected: 6.6
Unaffected: 0 , < 6.6 (semver)
Unaffected: 6.6.136 , ≤ 6.6.* (semver)
Unaffected: 6.12.83 , ≤ 6.12.* (semver)
Unaffected: 6.18.24 , ≤ 6.18.* (semver)
Unaffected: 6.19.14 , ≤ 6.19.* (semver)
Unaffected: 7.0.1 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "9a9bdaf9dc42ccca50e53f82165292f74a365c11",
              "status": "affected",
              "version": "0934d37596151edce115c6d0843a9ad7d5e5d232",
              "versionType": "git"
            },
            {
              "lessThan": "a8a55913552aed45108525d1851c65e1db0cc25b",
              "status": "affected",
              "version": "0934d37596151edce115c6d0843a9ad7d5e5d232",
              "versionType": "git"
            },
            {
              "lessThan": "f99353cd0e9f58bf17889049137b8d65fb44ebf1",
              "status": "affected",
              "version": "0934d37596151edce115c6d0843a9ad7d5e5d232",
              "versionType": "git"
            },
            {
              "lessThan": "93d9a58961a9e09306857e999b3ee76aa4be67f0",
              "status": "affected",
              "version": "0934d37596151edce115c6d0843a9ad7d5e5d232",
              "versionType": "git"
            },
            {
              "lessThan": "f1692337c6fa26e04f89b22a4d84bf5b7ada50d1",
              "status": "affected",
              "version": "0934d37596151edce115c6d0843a9ad7d5e5d232",
              "versionType": "git"
            },
            {
              "lessThan": "76e35091ffc722ba39b303e48bc5d08abb59dd56",
              "status": "affected",
              "version": "0934d37596151edce115c6d0843a9ad7d5e5d232",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.6"
            },
            {
              "lessThan": "6.6",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.136",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.83",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.24",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.14",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.1",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.136",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.83",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.24",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.14",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.1",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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-\u003eencode_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-\u003edev-\u003eencode_workqueue, \u0026ctx-\u003eencode_work)\nThe worker function accesses ctx-\u003em2m_ctx, ctx-\u003edev, 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(\u0026ctx-\u003eencode_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(\u0026ctx-\u003elist). 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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-14T17:42:16.125Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/9a9bdaf9dc42ccca50e53f82165292f74a365c11"
        },
        {
          "url": "https://git.kernel.org/stable/c/a8a55913552aed45108525d1851c65e1db0cc25b"
        },
        {
          "url": "https://git.kernel.org/stable/c/f99353cd0e9f58bf17889049137b8d65fb44ebf1"
        },
        {
          "url": "https://git.kernel.org/stable/c/93d9a58961a9e09306857e999b3ee76aa4be67f0"
        },
        {
          "url": "https://git.kernel.org/stable/c/f1692337c6fa26e04f89b22a4d84bf5b7ada50d1"
        },
        {
          "url": "https://git.kernel.org/stable/c/76e35091ffc722ba39b303e48bc5d08abb59dd56"
        }
      ],
      "title": "media: mediatek: vcodec: fix use-after-free in encoder release path",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31584",
    "datePublished": "2026-04-24T14:42:13.586Z",
    "dateReserved": "2026-03-09T15:48:24.120Z",
    "dateUpdated": "2026-06-14T17:42:16.125Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-31584",
      "date": "2026-06-16",
      "epss": "0.00126",
      "percentile": "0.02564"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-31584\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-04-24T15:16:33.117\",\"lastModified\":\"2026-04-27T20:20:32.087\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"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-\u003eencode_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-\u003edev-\u003eencode_workqueue, \u0026ctx-\u003eencode_work)\\nThe worker function accesses ctx-\u003em2m_ctx, ctx-\u003edev, 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(\u0026ctx-\u003eencode_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(\u0026ctx-\u003elist). 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.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-416\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionEndExcluding\":\"6.6.136\",\"matchCriteriaId\":\"14109CEF-714B-4029-A318-97AA58A01833\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.12\",\"versionEndExcluding\":\"6.12.83\",\"matchCriteriaId\":\"A8BAD957-8E20-401C-A129-DFF3655CA0B7\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.18.24\",\"matchCriteriaId\":\"8126B8B8-6D0B-4443-86C1-672AEE893555\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.19\",\"versionEndExcluding\":\"6.19.14\",\"matchCriteriaId\":\"D6A8A074-BBF4-4803-ABED-519A839435BB\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"7.0\",\"versionEndExcluding\":\"7.0.1\",\"matchCriteriaId\":\"9B5888AB-7403-4335-89E4-21CC0B48366A\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/76e35091ffc722ba39b303e48bc5d08abb59dd56\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/93d9a58961a9e09306857e999b3ee76aa4be67f0\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/9a9bdaf9dc42ccca50e53f82165292f74a365c11\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/a8a55913552aed45108525d1851c65e1db0cc25b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/f1692337c6fa26e04f89b22a4d84bf5b7ada50d1\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/f99353cd0e9f58bf17889049137b8d65fb44ebf1\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}"
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.