Commit 8f9dcc29 authored by Ahmed Zaki's avatar Ahmed Zaki Committed by Johannes Berg
Browse files

mac80211: fix a memory leak where sta_info is not freed 



The following is from a system that went OOM due to a memory leak:

wlan0: Allocated STA 74:83:c2:64:0b:87
wlan0: Allocated STA 74:83:c2:64:0b:87
wlan0: IBSS finish 74:83:c2:64:0b:87 (---from ieee80211_ibss_add_sta)
wlan0: Adding new IBSS station 74:83:c2:64:0b:87
wlan0: moving STA 74:83:c2:64:0b:87 to state 2
wlan0: moving STA 74:83:c2:64:0b:87 to state 3
wlan0: Inserted STA 74:83:c2:64:0b:87
wlan0: IBSS finish 74:83:c2:64:0b:87 (---from ieee80211_ibss_work)
wlan0: Adding new IBSS station 74:83:c2:64:0b:87
wlan0: moving STA 74:83:c2:64:0b:87 to state 2
wlan0: moving STA 74:83:c2:64:0b:87 to state 3
.
.
wlan0: expiring inactive not authorized STA 74:83:c2:64:0b:87
wlan0: moving STA 74:83:c2:64:0b:87 to state 2
wlan0: moving STA 74:83:c2:64:0b:87 to state 1
wlan0: Removed STA 74:83:c2:64:0b:87
wlan0: Destroyed STA 74:83:c2:64:0b:87

The ieee80211_ibss_finish_sta() is called twice on the same STA from 2
different locations. On the second attempt, the allocated STA is not
destroyed creating a kernel memory leak.

This is happening because sta_info_insert_finish() does not call
sta_info_free() the second time when the STA already exists (returns
-EEXIST). Note that the caller sta_info_insert_rcu() assumes STA is
destroyed upon errors.

Same fix is applied to -ENOMEM.

Signed-off-by: default avatarAhmed Zaki <anzaki@gmail.com>
Link: https://lore.kernel.org/r/20211002145329.3125293-1-anzaki@gmail.com


[change the error path label to use the existing code]
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 942bd107

net/mac80211/sta_info.c

+3 −3
Original line number Diff line number Diff line
@@ -644,13 +644,13 @@ static int sta_info_insert_finish(struct sta_info *sta) __acquires(RCU) 
	/* check if STA exists already */

	if (sta_info_get_bss(sdata, sta->sta.addr)) {

		err = -EEXIST;

		goto out_err;

		goto out_cleanup;

	}



	sinfo = kzalloc(sizeof(struct station_info), GFP_KERNEL);

	if (!sinfo) {

		err = -ENOMEM;

		goto out_err;

		goto out_cleanup;

	}



	local->num_sta++;
@@ -706,8 +706,8 @@ static int sta_info_insert_finish(struct sta_info *sta) __acquires(RCU) 
 out_drop_sta:

	local->num_sta--;

	synchronize_net();

 out_cleanup:

	cleanup_single_sta(sta);

 out_err:

	mutex_unlock(&local->sta_mtx);

	kfree(sinfo);

	rcu_read_lock();