Linux Kernel Bluetooth Flow Control Mismanagement Vulnerability on SAMA5D27 Platform

A vulnerability in the Linux kernel's handling of Bluetooth flow control has been identified on the Atmel SAMA5D27 platform. The issue arises in the atmel_serial driver, which improperly manages flow control signals in a way that can interfere with the normal operation of the device. This mismanagement can lead to unexpected behavior in the Bluetooth stack, potentially causing disruptions in wireless communication.

Impact

The vulnerability can cause improper handling of Bluetooth flow control, leading to potential disruptions in wireless communication on the affected device.

Reproduction

The vulnerability can be reproduced by using the atmel_serial driver on a SAMA5D27 platform. When the driver attempts to toggle flow control settings in a context that does not allow for such operations, the kernel emits a warning. This situation can occur if the flow control is managed while the device interrupts are disabled, which some tty drivers do when configuring modem line settings.

Remediation

The vulnerability has been addressed by modifying the atmel_serial driver to separate the flow control disable function into synchronous and asynchronous versions. Users should ensure they are using a patched version of the driver that incorporates this change.