From 8f9dcc29566626f683843ccac6113a12208315ca Mon Sep 17 00:00:00 2001
From: Ahmed Zaki <anzaki@gmail.com>
Date: Sat, 2 Oct 2021 08:53:29 -0600
Subject: [PATCH] mac80211: fix a memory leak where sta_info is not freed
Git-commit: 8f9dcc29566626f683843ccac6113a12208315ca
Patch-mainline: v5.16-rc6
References: git-fixes

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

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: expiring inactive not authorized STA 74:83:c2:64:0b:87
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: Ahmed 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: Johannes Berg <johannes.berg@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 net/mac80211/sta_info.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 51b49f0d3ad4..840ad1a860fa 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -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();
-- 
2.35.3