Affected: Linux

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

wifi: mac80211: disconnect on CSA to channel 0

The refactor for the CSA parsing erroneously equates channel zero and no information present, leading it to ignore a CSA on an AP that advertises a switch to that (invalid) channel. This leads to not disconnecting, which we should. For Intel devices, this can lead to a firmware crash.

Fix this by using an int type for the channel number as well as the opclass, and using a (negative) value that cannot be encoded in the element to indicate it's not present.