CVE-2024-58238

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

Bluetooth: btnxpuart: Resolve TX timeout error in power save stress test

This fixes the tx timeout issue seen while running a stress test on btnxpuart for couple of hours, such that the interval between two HCI commands coincide with the power save timeout value of 2 seconds.

Test procedure using bash script: <load btnxpuart.ko> hciconfig hci0 up //Enable Power Save feature hcitool -i hci0 cmd 3f 23 02 00 00 while (true) do hciconfig hci0 leadv sleep 2 hciconfig hci0 noleadv sleep 2 done

Error log, after adding few more debug prints: Bluetooth: btnxpuart_queue_skb(): 01 0A 20 01 00 Bluetooth: hci0: Set UART break: on, status=0 Bluetooth: hci0: btnxpuart_tx_wakeup() tx_work scheduled Bluetooth: hci0: btnxpuart_tx_work() dequeue: 01 0A 20 01 00 Can't set advertise mode on hci0: Connection timed out (110) Bluetooth: hci0: command 0x200a tx timeout

When the power save mechanism turns on UART break, and btnxpuart_tx_work() is scheduled simultaneously, psdata->ps_state is read as PS_STATE_AWAKE, which prevents the psdata->work from being scheduled, which is responsible to turn OFF UART break.

This issue is fixed by adding a ps_lock mutex around UART break on/off as well as around ps_state read/write. btnxpuart_tx_wakeup() will now read updated ps_state value. If ps_state is PS_STATE_SLEEP, it will first schedule psdata->work, and then it will reschedule itself once UART break has been turned off and ps_state is PS_STATE_AWAKE.

Tested above script for 50,000 iterations and TX timeout error was not observed anymore.

This vulnerability is rated with a Moderate severity rather than Important because exploitation requires local access and is restricted to systems utilizing specialized NXP Bluetooth UART hardware, bounding the blast radius to a localized denial of service. In standard Red Hat Enterprise Linux deployments, this driver is not engaged unless the specific transceiver hardware is present and active. An anomalous sequence of power-management operations can cause transmitter timeouts, resulting in loss of Bluetooth communication without impacting host confidentiality or integrity.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.