From: Johannes Berg <johannes@sipsolutions.net>
Date: Mon, 25 Feb 2008 15:27:42 +0000 (+0100)
Subject: mac80211: safely free beacon in ieee80211_if_reinit
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=e6a5ddf20886206caf1c4a2431f6ff01198ab0f7;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git

mac80211: safely free beacon in ieee80211_if_reinit

If ieee80211_if_reinit() is called from ieee80211_unregister_hw()
then it is possible that the driver will still request a beacon
(it is allowed to until ieee80211_unregister_hw() has returned.)
This means we need to use an RCU-protected write to the beacon
information even in this function.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
---

diff --git a/net/mac80211/ieee80211_iface.c b/net/mac80211/ieee80211_iface.c
index f66f1ddc3fda..0d6824bca92b 100644
--- a/net/mac80211/ieee80211_iface.c
+++ b/net/mac80211/ieee80211_iface.c
@@ -193,6 +193,7 @@ void ieee80211_if_reinit(struct net_device *dev)
 		/* Remove all virtual interfaces that use this BSS
 		 * as their sdata->bss */
 		struct ieee80211_sub_if_data *tsdata, *n;
+		struct beacon_data *beacon;
 
 		list_for_each_entry_safe(tsdata, n, &local->interfaces, list) {
 			if (tsdata != sdata && tsdata->bss == &sdata->u.ap) {
@@ -210,7 +211,10 @@ void ieee80211_if_reinit(struct net_device *dev)
 			}
 		}
 
-		kfree(sdata->u.ap.beacon);
+		beacon = sdata->u.ap.beacon;
+		rcu_assign_pointer(sdata->u.ap.beacon, NULL);
+		synchronize_rcu();
+		kfree(beacon);
 
 		while ((skb = skb_dequeue(&sdata->u.ap.ps_bc_buf))) {
 			local->total_ps_buffered--;