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

net: atm: reject out-of-range traffic classes in QoS validation

Reject ATM traffic classes above ATM_ANYCLASS in check_tp().
SO_ATMQOS stores the supplied QoS after check_qos() succeeds, so
accepting larger values leaves invalid traffic_class values in
vcc->qos.

That bad state later reaches pvc_info(), which indexes class_name[]
with vcc->qos.{rx,tp}.traffic_class. Values above ATM_ANYCLASS cause
an out-of-bounds read when /proc/net/atm/pvc is read.

Tighten the existing QoS validation so invalid traffic_class values
are rejected at the point where user supplied QoS is accepted.