GHSA-QXC2-9RG4-2RGV
Vulnerability from github – Published: 2026-05-28 12:30 – Updated: 2026-06-01 18:31In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: virtio_bt: clamp rx length before skb_put
virtbt_rx_work() calls skb_put(skb, len) where len comes directly from virtqueue_get_buf() with no validation against the buffer we posted to the device. The RX skb is allocated in virtbt_add_inbuf() and exposed to virtio as exactly 1000 bytes via sg_init_one().
Checking len against skb_tailroom(skb) is not sufficient because alloc_skb() can leave more tailroom than the 1000 bytes actually handed to the device. A malicious or buggy backend can therefore report used.len between 1001 and skb_tailroom(skb), causing skb_put() to include uninitialized kernel heap bytes that were never written by the device.
The same path also accepts len == 0, in which case skb_put(skb, 0) leaves the skb empty but virtbt_rx_handle() still reads the pkt_type byte from skb->data, consuming uninitialized memory.
Define VIRTBT_RX_BUF_SIZE once and reuse it in alloc_skb() and sg_init_one(), and gate virtbt_rx_work() on that same constant so the bound checked matches the buffer actually exposed to the device. Reject used.len == 0 in the same gate so an empty completion can no longer reach virtbt_rx_handle().
Use bt_dev_err_ratelimited() because the length value comes from an untrusted backend that can otherwise flood the kernel log.
Same class of bug as commit c04db81cd028 ("net/9p: Fix buffer overflow in USB transport layer"), which hardened the USB 9p transport against unchecked device-reported length.
{
"affected": [],
"aliases": [
"CVE-2026-46123"
],
"database_specific": {
"cwe_ids": [
"CWE-787"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-05-28T10:16:27Z",
"severity": "HIGH"
},
"details": "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-\u003edata, 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.",
"id": "GHSA-qxc2-9rg4-2rgv",
"modified": "2026-06-01T18:31:37Z",
"published": "2026-05-28T12:30:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-46123"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/21bd244b6de5d2fe1063c23acc93fbdd2b20d112"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4236e55b2d9d1ffd3b4bdf8ebbb86e5a0a526b4a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6c1730099a6fc18b183bd6c1adad3b54adcaeda9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b40cdd1b1370d76e9e760af4490cb4a351cceead"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e6b4296f170d949ebba937cf6a3f247ec9550d2c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ed41c81d30b211a671667259c3b5feeba0e062d5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fd91fa2678ab603dfb285416c1cf3843d7be1e41"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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