Linux Kernel Bluetooth Unknown Command Complete Event Length Validation Vulnerability

A vulnerability exists in the Linux kernel's Bluetooth subsystem, specifically in the handling of command complete events with unknown opcodes. When such an event occurs, the first byte of the remaining data is assumed to contain the return status. However, the parameter data may have been cleared by a previous function, potentially leaving the data buffer empty. This can result in reading uninitialized memory, leading to undefined behavior. The issue has been addressed by adding a check for the data length before accessing the return status byte.

Impact

Exploitation of this vulnerability could lead to the use of uninitialized memory, which may cause unpredictable behavior in the application or system.

Reproduction

The vulnerability can be reproduced by sending a command complete event with an unknown opcode through the Bluetooth HCI interface. The event should be processed by the 'hci_cmd_complete_evt' function, which will attempt to read the return status from the event data. If the data length is zero, indicating that no status is available, the function will still try to access the first byte, resulting in the use of uninitialized memory.

Remediation

Users can upgrade to the latest version of the Linux kernel where this vulnerability has been fixed. Instructions for downloading the patched version are available on the official Linux kernel website.