CVE-2022-41972: low-severity vulnerability in contiki-ng

Contiki-NG is an open-source, cross-platform operating system for Next-Generation IoT devices. Versions prior to 4.9 contain a NULL Pointer Dereference in BLE L2CAP module. The Contiki-NG operating system for IoT devices contains a Bluetooth Low Energy stack. An attacker can inject a packet in this stack, which causes the implementation to dereference a NULL pointer and triggers undefined behavior. More specifically, while processing the L2CAP protocol, the implementation maps an incoming channel ID to its metadata structure. In this structure, state information regarding credits is managed through calls to the function input_l2cap_credit in the module os/net/mac/ble/ble-l2cap.c. Unfortunately, the input_l2cap_credit function does not check that the metadata corresponding to the user-supplied channel ID actually exists, which can lead to the channel variable being set to NULL before a pointer dereferencing operation is performed. The vulnerability has been patched in the "develop" branch of Contiki-NG, and will be included in release 4.9. Users can apply the patch in Contiki-NG pull request #2253 as a workaround until the new package is released.