CVE-2023-53386

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

Bluetooth: Fix potential use-after-free when clear keys

Similar to commit c5d2b6fa26b5 ("Bluetooth: Fix use-after-free in hci_remove_ltk/hci_remove_irk"). We can not access k after kfree_rcu() call.

A use-after-free bug was identified in the Bluetooth stack when clearing link and security keys. The code iterated with list_for_each_entry() and freed items with kfree_rcu(), allowing access to freed memory. A local user with Bluetooth administration privileges (e.g. able to unpair devices, reset the adapter or manage stored keys) can reliably trigger this bug, causing use-after-free and likely DoS/kernel crash. And the confidential data leakage from freed memory is theoretically possible. Triggering this remotely is difficult — an unauthenticated/unknown device generally cannot force the kernel to clear those local key lists — and would realistically require a device that is already paired/authenticated (or otherwise an exploit chain) to influence the same code paths.

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.

To mitigate these vulnerabilities on the operating system level, disable the Bluetooth functionality via blocklisting kernel modules in the Linux kernel. The kernel modules can be prevented from being loaded by using system-wide modprobe rules. Instructions on how to disable Bluetooth modules are available on the customer portal at https://access.redhat.com/solutions/2682931.

Alternatively, bluetooth can be disabled within the hardware or at the BIOS level, which will also provide effective mitigation as the kernel will not detect Bluetooth hardware on the system.