Patch "mac80211: fix divide by zero when NOA update" has been added to the 4.2-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    mac80211: fix divide by zero when NOA update

to the 4.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mac80211-fix-divide-by-zero-when-noa-update.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 519ee6918b91abdc4bc9720deae17599a109eb40 Mon Sep 17 00:00:00 2001
From: "Janusz.Dziedzic@tieto.com" <Janusz.Dziedzic@tieto.com>
Date: Tue, 27 Oct 2015 08:35:11 +0100
Subject: mac80211: fix divide by zero when NOA update

From: "Janusz.Dziedzic@tieto.com" <Janusz.Dziedzic@tieto.com>

commit 519ee6918b91abdc4bc9720deae17599a109eb40 upstream.

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
[...]

Signed-off-by: Janusz Dziedzic <janusz.dziedzic@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/mac80211/util.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -2984,6 +2984,13 @@ ieee80211_extend_noa_desc(struct ieee802
 	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) {


Patches currently in stable-queue which might be from Janusz.Dziedzic@tieto.com are

queue-4.2/mac80211-fix-divide-by-zero-when-noa-update.patch