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Ignore channel switch event if AP interface is not yet ready 

It is apparently possible to somehow trigger the driver to report a
channel switch event during ACS operation when the interface information
is not yet complete. hapd->iface->current_mode could be NULL in that
case and that would result in process termination due to NULL pointer
dereference.

It should not really be possible to trigger a channel switch during ACS
is running (i.e., before the AP mode operation has been started), but
since that has been seen in an arbitrary test sequence with interface
start/stop operations with various parameters (both valid and invalid),
better prevent a crash here by ignoring the unexpected event instead of
trying to process it.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
This commit is contained in:
Jouni Malinen 2019-04-26 16:24:31 +03:00 committed by Jouni Malinen
parent eb314e8af2
commit c3805fb623
1 changed files with 7 additions and 0 deletions
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7
src/ap/drv_callbacks.c
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@ -789,6 +789,13 @@ void hostapd_event_ch_switch(struct hostapd_data *hapd, int freq, int ht,
freq, ht, hapd->iconf->ch_switch_vht_config, offset,
width, channel_width_to_string(width), cf1, cf2);
if (!hapd->iface->current_mode) {
hostapd_logger(hapd, NULL, HOSTAPD_MODULE_IEEE80211,
HOSTAPD_LEVEL_WARNING,
"ignore channel switch since the interface is not yet ready");
return;
}
hapd->iface->freq = freq;
channel = hostapd_hw_get_channel(hapd, freq);