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>
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index d767cfb..1f7d842 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -893,10 +893,15 @@
/* 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),