[PATCH AUTOSEL 5.9 045/147] staging: wfx: fix potential use before init

Sasha Levin
2020-10-27T00:41:42Z

From: Jérôme Pouiller <jerome.pouiller@silabs.com>

[ Upstream commit ce3653a8d3db096aa163fc80239d8ec1305c81fa ]

The trace below can appear:

[83613.832200] INFO: trying to register non-static key.
[83613.837248] the code is fine but needs lockdep annotation.
[83613.842808] turning off the locking correctness validator.
[83613.848375] CPU: 3 PID: 141 Comm: kworker/3:2H Tainted: G O 5.6.13-silabs15 #2
[83613.857019] Hardware name: BCM2835
[83613.860605] Workqueue: events_highpri bh_work [wfx]
[83613.865552] Backtrace:
[83613.868041] [<c010f2cc>] (dump_backtrace) from [<c010f7b8>] (show_stack+0x20/0x24)
[83613.881463] [<c010f798>] (show_stack) from [<c0d82138>] (dump_stack+0xe8/0x114)
[83613.888882] [<c0d82050>] (dump_stack) from [<c01a02ec>] (register_lock_class+0x748/0x768)
[83613.905035] [<c019fba4>] (register_lock_class) from [<c019da04>] (__lock_acquire+0x88/0x13dc)
[83613.924192] [<c019d97c>] (__lock_acquire) from [<c019f6a4>] (lock_acquire+0xe8/0x274)
[83613.942644] [<c019f5bc>] (lock_acquire) from [<c0daa5dc>] (_raw_spin_lock_irqsave+0x58/0x6c)
[83613.961714] [<c0daa584>] (_raw_spin_lock_irqsave) from [<c0ab3248>] (skb_dequeue+0x24/0x78)
[83613.974967] [<c0ab3224>] (skb_dequeue) from [<bf330db0>] (wfx_tx_queues_get+0x96c/0x1294 [wfx])
[83613.989728] [<bf330444>] (wfx_tx_queues_get [wfx]) from [<bf320454>] (bh_work+0x454/0x26d8 [wfx])
[83614.009337] [<bf320000>] (bh_work [wfx]) from [<c014c920>] (process_one_work+0x23c/0x7ec)
[83614.028141] [<c014c6e4>] (process_one_work) from [<c014cf1c>] (worker_thread+0x4c/0x55c)
[83614.046861] [<c014ced0>] (worker_thread) from [<c0154c04>] (kthread+0x138/0x168)
[83614.064876] [<c0154acc>] (kthread) from [<c01010b4>] (ret_from_fork+0x14/0x20)
[83614.072200] Exception stack(0xecad3fb0 to 0xecad3ff8)
[83614.077323] 3fa0: 00000000 00000000 00000000 00000000
[83614.085620] 3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[83614.093914] 3fe0: 00000000 00000000 00000000 00000000 00000013 00000000

Indeed, the code of wfx_add_interface() shows that the interface is
enabled to early. So, the spinlock associated with some skb_queue may
not yet initialized when wfx_tx_queues_get() is called.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200825085828.399505-8-Jerome.Pouiller@silabs.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/staging/wfx/sta.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/staging/wfx/sta.c b/drivers/staging/wfx/sta.c
index 4e30ab17a93d4..b96c83671caeb 100644
--- a/drivers/staging/wfx/sta.c
+++ b/drivers/staging/wfx/sta.c
@@ -760,17 +760,6 @@ int wfx_add_interface(struct ieee80211_hw *hw, struct ieee80211_vif *vif)
return -EOPNOTSUPP;
}

- for (i = 0; i < ARRAY_SIZE(wdev->vif); i++) {
- if (!wdev->vif[i]) {
- wdev->vif[i] = vif;
- wvif->id = i;
- break;
- }
- }
- if (i == ARRAY_SIZE(wdev->vif)) {
- mutex_unlock(&wdev->conf_mutex);
- return -EOPNOTSUPP;
- }
// FIXME: prefer use of container_of() to get vif
wvif->vif = vif;
wvif->wdev = wdev;
@@ -787,12 +776,22 @@ int wfx_add_interface(struct ieee80211_hw *hw, struct ieee80211_vif *vif)
init_completion(&wvif->scan_complete);
INIT_WORK(&wvif->scan_work, wfx_hw_scan_work);

- mutex_unlock(&wdev->conf_mutex);
+ wfx_tx_queues_init(wvif);
+ wfx_tx_policy_init(wvif);
+
+ for (i = 0; i < ARRAY_SIZE(wdev->vif); i++) {
+ if (!wdev->vif[i]) {
+ wdev->vif[i] = vif;
+ wvif->id = i;
+ break;
+ }
+ }
+ WARN(i == ARRAY_SIZE(wdev->vif), "try to instantiate more vif than supported");

hif_set_macaddr(wvif, vif->addr);

- wfx_tx_queues_init(wvif);
- wfx_tx_policy_init(wvif);
+ mutex_unlock(&wdev->conf_mutex);
+
wvif = NULL;
while ((wvif = wvif_iterate(wdev, wvif)) != NULL) {
// Combo mode does not support Block Acks. We can re-enable them
@@ -824,6 +823,7 @@ void wfx_remove_interface(struct ieee80211_hw *hw, struct ieee80211_vif *vif)
wvif->vif = NULL;

mutex_unlock(&wdev->conf_mutex);
+
wvif = NULL;
while ((wvif = wvif_iterate(wdev, wvif)) != NULL) {
// Combo mode does not support Block Acks. We can re-enable them
--
2.25.1