CVE-2026-98702: wifi: mac80211: reject invalid 320 MHz CSA bandwidth

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

wifi: mac80211: reject invalid 320 MHz CSA bandwidth

The HT/VHT channel definition validator can receive a 320 MHz bandwidth indication from a received CSA frame on a non-6 GHz link. It warns for this unsupported width but continues with an uninitialized vhtoperation.chanwidth, which is then read by ieee80211chandefvhtoper(). With paniconwarn enabled, this lets a received frame panic the kernel.

Reject the channel definition before entering the VHT operation conversion. This preserves the existing CSA fallback while avoiding both the warning and the uninitialized read.