In 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.
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.
Metrics
Affected Vendors & Products
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Thu, 17 Sep 2026 16:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In 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. | |
| Title | Bluetooth: btmtksdio: Fix out-of-bounds DMA read in the TX path | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-17T16:06:04.844Z
Reserved: 2026-09-11T19:38:34.786Z
Link: CVE-2026-90090
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-17T17:17:00.340
Modified: 2026-09-17T17:17:00.340
Link: CVE-2026-90090
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.