GHSA-V2Q7-G7PP-VM78
Vulnerability from github – Published: 2026-09-17 18:31 – Updated: 2026-09-17 18:31In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: btmtksdio: Fix out-of-bounds DMA read in the TX path
btmtksdio_tx_packet() rounds the transfer size up to the SDIO block size of 256 bytes, but hands the host controller the SKB buffer as is:
err = sdio_writesb(bdev->func, MTK_REG_CTDR, skb->data,
round_up(skb->len, MTK_SDIO_BLOCK_SIZE));
Only skb->len bytes hold packet data, so the controller reads up to 255 bytes of uninitialised memory and sends it to the device over the SDIO bus. Depending on how much tailroom slack the SKB allocation happens to carry, that read can also extend past the end of the buffer.
Compute the padded length up front, ensure the SKB has tailroom for it, and zero-fill the padding with skb_put_zero(). skb->len then covers the padding, so sdio_writesb() no longer needs to round up. byte_tx keeps counting the header and the payload only, and the error path restores the SKB so that the caller can requeue it.
Writing behind skb->tail is only safe because the driver owns the buffer, which "Bluetooth: btmtksdio: Take exclusive ownership of the SKB before TX" ensures.
{
"affected": [],
"aliases": [
"CVE-2026-90090"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:17:00Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: btmtksdio: Fix out-of-bounds DMA read in the TX path\n\nbtmtksdio_tx_packet() rounds the transfer size up to the SDIO block size\nof 256 bytes, but hands the host controller the SKB buffer as is:\n\n\terr = sdio_writesb(bdev-\u003efunc, MTK_REG_CTDR, skb-\u003edata,\n\t\t\t round_up(skb-\u003elen, MTK_SDIO_BLOCK_SIZE));\n\nOnly skb-\u003elen bytes hold packet data, so the controller reads up to 255\nbytes of uninitialised memory and sends it to the device over the SDIO\nbus. Depending on how much tailroom slack the SKB allocation happens to\ncarry, that read can also extend past the end of the buffer.\n\nCompute the padded length up front, ensure the SKB has tailroom for it,\nand zero-fill the padding with skb_put_zero(). skb-\u003elen then covers the\npadding, so sdio_writesb() no longer needs to round up. byte_tx keeps\ncounting the header and the payload only, and the error path restores the\nSKB so that the caller can requeue it.\n\nWriting behind skb-\u003etail is only safe because the driver owns the buffer,\nwhich \"Bluetooth: btmtksdio: Take exclusive ownership of the SKB before\nTX\" ensures.",
"id": "GHSA-v2q7-g7pp-vm78",
"modified": "2026-09-17T18:31:50Z",
"published": "2026-09-17T18:31:50Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90090"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0b71a6caaf284915c8cf9cd320ecee9f0361824a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7b37556d7d801b79096c7ba8ea92db2338aa8b00"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7b80d2701a68456c536f82e577dbed2f60ccb82b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9a785ea864214aaffd8300683825c3f788d0b634"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c8742f53c9ef623decd5285403df0e5b5273c9fd"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fa0ad2d277c7adead61d1c22411c55cea6990c2a"
}
],
"schema_version": "1.4.0",
"severity": []
}
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