minor array overflow in ifconfig set80211chanlist()

[Don Lewis]

I asked adrian@ privately and he sent me here ...

Coverity is complaining about an array overflow in set80211chanlist().

The code in question is:
                        if (first > IEEE80211_CHAN_MAX)
                                errx(-1, "channel %u out of range, max %u",
                                        first, IEEE80211_CHAN_MAX);
                        setbit(chanlist.ic_channels, first);

The value of IEEE80211_CHAN_MAX is 256, so first could be as large as
256 and setbit() would still be called.

The ifconfig man page says that channel numbers should be in the range
1 to 255, so I think the correct fix would be to change this test (as
well as others that follow) to >= IEEE80211_CHAN_MAX.

Does that look correct?

Adrian suggested that maybe IEEE80211_CHAN_MAX should be 255.