Commit 519ee691 authored Oct 27, 2015 by Janusz.Dziedzic@tieto.com Committed by Johannes Berg Nov 03, 2015

mac80211: fix divide by zero when NOA update



In case of one shot NOA the interval can be 0, catch that
instead of potentially (depending on the driver) crashing
like this:

divide error: 0000 [#1] SMP
[...]
Call Trace:
<IRQ>
[<ffffffffc08e891c>] ieee80211_extend_absent_time+0x6c/0xb0 [mac80211]
[<ffffffffc08e8a17>] ieee80211_update_p2p_noa+0xb7/0xe0 [mac80211]
[<ffffffffc069cc30>] ath9k_p2p_ps_timer+0x170/0x190 [ath9k]
[<ffffffffc070adf8>] ath_gen_timer_isr+0xc8/0xf0 [ath9k_hw]
[<ffffffffc0691156>] ath9k_tasklet+0x296/0x2f0 [ath9k]
[<ffffffff8107ad65>] tasklet_action+0xe5/0xf0
[...]

Cc: stable@vger.kernel.org [3.16+, due to d463af4a using it]
Signed-off-by: Janusz Dziedzic <janusz.dziedzic@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

parent e9829b97

net/mac80211/util.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -2958,6 +2958,13 @@ ieee80211_extend_noa_desc(struct ieee80211_noa_data *data, u32 tsf, int i)
		if (end > 0)
		return false;

		/* One shot NOA */
		if (data->count[i] == 1)
		return false;

		if (data->desc[i].interval == 0)
		return false;

		/* End time is in the past, check for repetitions */
		skip = DIV_ROUND_UP(-end, data->desc[i].interval);
		if (data->count[i] < 255) {

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