[PATCH v2 1/6] staging: rtl8188eu: use safe iterator in rtw_free_network_queue

Martin Kaiser
2021-05-17T20:20:37Z

rtw_free_network_queue iterates over the scanned wireless networks and
calls _rtw_free_network for each of them. In some cases,
_rtw_free_network removes a network from the list.

We have to use list_for_each_entry_safe if we remove list entries while
we iterate over a list.

Fixes: 23017c8842d2 ("staging: rtl8188eu: Use list iterators and helpers")
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
---
v2:
- use list_for_each_entry_safe

Without this patch, it's easy to get the driver into an endless loop by
scanning, connecting and disconnecting repeatedly.

wpa_supplicant -B -Dwext -i wlan0 -c /path/to/my/config...
while true ; do
sleep 1
wpa_cli reconfigure
wpa_cli add_network
wpa_cli set_network 0 ssid ...
wpa_cli set_network 0 psk ...
wpa_cli select_network 0
sleep 6
wpa_cli status
wpa_cli disconnect 0
done

drivers/staging/rtl8188eu/core/rtw_mlme.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/rtl8188eu/core/rtw_mlme.c b/drivers/staging/rtl8188eu/core/rtw_mlme.c
index 159465b073c2..ba73ac5325e2 100644
--- a/drivers/staging/rtl8188eu/core/rtw_mlme.c
+++ b/drivers/staging/rtl8188eu/core/rtw_mlme.c
@@ -199,19 +199,17 @@ struct wlan_network *rtw_find_network(struct __queue *scanned_queue, u8 *addr)

void rtw_free_network_queue(struct adapter *padapter, u8 isfreeall)
{
- struct list_head *phead, *plist;
- struct wlan_network *pnetwork;
+ struct list_head *phead;
+ struct wlan_network *pnetwork, *temp;
struct mlme_priv *pmlmepriv = &padapter->mlmepriv;
struct __queue *scanned_queue = &pmlmepriv->scanned_queue;

spin_lock_bh(&scanned_queue->lock);

phead = get_list_head(scanned_queue);
- list_for_each(plist, phead) {
- pnetwork = list_entry(plist, struct wlan_network, list);
-
+ list_for_each_entry_safe(pnetwork, temp, phead, list)
_rtw_free_network(pmlmepriv, pnetwork, isfreeall);
- }
+
spin_unlock_bh(&scanned_queue->lock);
}

--
2.20.1