Commit 52512072 authored Jan 19, 2014 by andrea merello Committed by Johannes Berg Feb 04, 2014

mac80211: add check on hw->max_signal value on ieee80211_register_hw



When IEEE80211_HW_SIGNAL_UNSPEC is set, mac80211 will perform a
division by max_signal in ieee80211_bss_info_update. If max_signal
is not properly set by the driver (for example it is zero) this
leads to a divide error and crash.
Thanks to Larry Finger, who pointed me to this.
This patch adds in ieee80211_register_hw one more check to detect
this condition and eventually returns -EINVAL, as already done for
other checks already performed there.

Signed-off-by: andrea merello <andrea.merello@gmail.com>
[move to an already existing SIGNAL_UNSPEC check]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

parent 30ef7ef9

net/mac80211/main.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -893,10 +893,15 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
		/* mac80211 supports control port protocol changing */
		local->hw.wiphy->flags \|= WIPHY_FLAG_CONTROL_PORT_PROTOCOL;

		if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
		if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM) {
		local->hw.wiphy->signal_type = CFG80211_SIGNAL_TYPE_MBM;
		else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
		} else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC) {
		local->hw.wiphy->signal_type = CFG80211_SIGNAL_TYPE_UNSPEC;
		if (hw->max_signal <= 0) {
		result = -EINVAL;
		goto fail_wiphy_register;
		}
		}

		WARN((local->hw.flags & IEEE80211_HW_SUPPORTS_UAPSD)
		&& (local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK),

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