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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>
This commit is contained in:
andrea merello 2014-01-19 22:21:49 +01:00 committed by Johannes Berg
parent 30ef7ef967
commit 5251207273
1 changed files with 7 additions and 2 deletions
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9
net/mac80211/main.c
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@ -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),