Bluetooth: virtio_bt: clamp rx length before skb_put_CVE-2026-46123

{
    "lastseen": "",
    "description": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: virtio_bt: clamp rx length before skb_put\n\nvirtbt_rx_work() calls skb_put(skb, len) where len comes directly\nfrom virtqueue_get_buf() with no validation against the buffer we\nposted to the device. The RX skb is allocated in virtbt_add_inbuf()\nand exposed to virtio as exactly 1000 bytes via sg_init_one().\n\nChecking len against skb_tailroom(skb) is not sufficient because\nalloc_skb() can leave more tailroom than the 1000 bytes actually\nhanded to the device. A malicious or buggy backend can therefore\nreport used.len between 1001 and skb_tailroom(skb), causing skb_put()\nto include uninitialized kernel heap bytes that were never written by\nthe device.\n\nThe same path also accepts len == 0, in which case skb_put(skb, 0)\nleaves the skb empty but virtbt_rx_handle() still reads the pkt_type\nbyte from skb->data, consuming uninitialized memory.\n\nDefine VIRTBT_RX_BUF_SIZE once and reuse it in alloc_skb() and\nsg_init_one(), and gate virtbt_rx_work() on that same constant so\nthe bound checked matches the buffer actually exposed to the device.\nReject used.len == 0 in the same gate so an empty completion can\nno longer reach virtbt_rx_handle().\n\nUse bt_dev_err_ratelimited() because the length value comes from an\nuntrusted backend that can otherwise flood the kernel log.\n\nSame class of bug as commit c04db81cd028 (\"net/9p: Fix buffer\noverflow in USB transport layer\"), which hardened the USB 9p\ntransport against unchecked device-reported length.",
    "published": "2026-05-28T09:35:38.003Z",
    "modified": "2026-05-30T10:48:01.376Z",
    "type": "cve",
    "title": "Bluetooth: virtio_bt: clamp rx length before skb_put",
    "source": "Linux",
    "references": "https://git.kernel.org/stable/c/ed41c81d30b211a671667259c3b5feeba0e062d5\nhttps://git.kernel.org/stable/c/6c1730099a6fc18b183bd6c1adad3b54adcaeda9\nhttps://git.kernel.org/stable/c/b40cdd1b1370d76e9e760af4490cb4a351cceead\nhttps://git.kernel.org/stable/c/e6b4296f170d949ebba937cf6a3f247ec9550d2c\nhttps://git.kernel.org/stable/c/21bd244b6de5d2fe1063c23acc93fbdd2b20d112",
    "id": "CVE-2026-46123",
    "bulletinFamily": "",
    "cwe": null,
    "cvelist": null,
    "sourceData": "Linux Linux 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be\nLinux Linux 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be\nLinux Linux 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be\nLinux Linux 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be\nLinux Linux 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be\nLinux Linux cf2719a21fdb9d4c8e9c834d279163609bef575d\nLinux Linux 9b67438e315b925a699f0178f4a48baf3d2d6ef4\nLinux Linux 5.15.78\nLinux Linux 6.0.8\nLinux Linux 6.1",
    "sourceHref": "",
    "cvss": {
        "score": 7.7,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
        "version": "3.1"
    },
    "cvss2": [],
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        "baseScore": 0,
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        "privilegesRequired": "",
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        "scope": "",
        "confidentialityImpact": "",
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        "availabilityImpact": "",
        "cvssV3": {
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    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Linux",
    "version": "160fbcf3bfb93c3c086427f9f4c8bc70f217e9be",
    "vendor": "Linux",
    "ai_description": "",
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    "ai_score": 0
}