CVE-2026-74508

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: HIDP: reject frames without a transaction header

hidp_recv_ctrl_frame() and hidp_recv_intr_frame() read skb->data[0] before checking that the L2CAP SDU contains a transaction header. A connected HIDP peer can send an empty basic-mode SDU and make both paths use an uninitialized byte from skb tailroom.

KMSAN reports the use in hidp_session_run(), with the uninitialized value originating in __alloc_skb() through vhci_write(). The control path produces two reports and the interrupt path produces one.

The byte can also be controlled by a malformed lower-layer packet. If an HCI ACL packet contains an L2CAP PDU with a declared zero-length payload followed by an extra 0x15 byte, l2cap_recv_acldata() reduces skb->len to the declared PDU length before dispatch. The current HIDP path nevertheless consumes the extra byte as HIDP_TRANS_HID_CONTROL | HIDP_CTRL_VIRTUAL_CABLE_UNPLUG and terminates the HIDP session. With this change, the same packet is discarded and a subsequent feature report request succeeds.

Pull the transaction header with skb_pull_data() and discard frames that do not contain it.

Affected Software

References

• https://git.kernel.org/stable/c/2ebf63aa557a69990b4e9ea22be224d58aabce96
• https://git.kernel.org/stable/c/46ca5ab39737d7c6f9ca77ecf714cdcfa6caaeec
• https://git.kernel.org/stable/c/47778d2c2087b5d192398f6fddf692d16a5431cf
• https://git.kernel.org/stable/c/854194494a6f726a60b90b76059148bf08df023d
• https://git.kernel.org/stable/c/97b61241ab45bfa5b0526cb0f3978942493bc811