{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-68370",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2026-68370"
  ],
  "published": "2026-08-10T12:08:00Z",
  "summary": "usb: gadget: dummy_hcd: prevent fifo_req reuse during giveback",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: dummy_hcd: prevent fifo_req reuse during giveback\n\ndummy_hcd embeds a single shared usb_request (dum->fifo_req) that the\n\"emulated single-request FIFO\" fast-path in dummy_queue() reuses for\nsmall IN transfers: it copies the caller's request into it\n(req->req = *_req) and queues it, treating list_empty(&fifo_req.queue)\nas \"the slot is free\".\n\nThe completion side (dummy_timer/transfer/nuke/dummy_dequeue) follows\nthe standard pattern: list_del_init(&req->queue) unlinks the request,\nthen the lock is dropped and usb_gadget_giveback_request() invokes\nreq->complete().  But list_del_init() makes fifo_req.queue look empty\n*before* the completion callback returns, so a concurrent dummy_queue()\non another CPU sees the slot as free, reuses fifo_req and runs\nreq->req = *_req -- overwriting req->complete while dummy_timer is\nmid-calling it.  The indirect call then jumps to a clobbered pointer,\ncausing a general protection fault / page fault in dummy_timer\n(syzkaller extid faf3a6cf579fc65591ca).  The clobbering write is an\nin-bounds memcpy on a live shared object, so KASAN cannot flag it.\n\nAdd a fifo_req_busy bit covering the shared request's whole lifetime:\nset it in dummy_queue() when the FIFO fast-path takes fifo_req (making\nit the fast-path guard, replacing the list_empty(&fifo_req.queue)\ntest), and clear it after the completion callback has returned, via a\ndummy_giveback() helper used at all four gadget-request giveback\nsites.  The shared slot can no longer be reused until its completion\ncallback has finished.",
  "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": "6.1.183",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-68370"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/16a685172abc9233728830e27d26ffa778975b51"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/95f30a21612cc65761c58ba044b1767699437317"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/3cab0e5498d0fbb21fe1a9181f7bda9a844a697e"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/e2b2740f1242bc70b5b46da2cdbbaa419f490e59"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/67b589d09a96882d56842dced5698ed8dd06ce45"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/e239ea91b48180ed48a86ac25643832a02c88456"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/e24b33618231034bf01dfaff4fd3409d4b4d5b2e"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/d5e5cd3654d2b5359a12ea6586120f05b28634ee"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-19T16:47:12Z"
  }
}