cfg80211: validate channel settings across interfaces
Currently, there's a problem that affects regulatory enforcement and connection stability, in that it is possible to switch the channel while connected to a network or joined to an IBSS. The problem comes from the fact that we only validate the channel against the current interface's type, not against any other interface. Thus, you have any type of interface up, additionally bring up a monitor mode interface and switch the channel on the monitor. This will obviously also switch the channel on the other interface. The problem now is that if you do that while sending beacons for IBSS mode, you can switch to a disabled channel or a channel that doesn't allow beaconing. Combined with a managed mode interface connected to an AP instead of an IBSS interface, you can easily break the connection that way. To fix this, this patch validates any channel change with all available interfaces, and disallows such changes on secondary interfaces if another interface is connected to an AP or joined to an IBSS. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>
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net/wireless/chan.c
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