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    Subject[PATCH 5.9 086/391] staging: wfx: fix potential use before init
    Date
    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 7dace7c17bf5c..536c62001c709 100644
    --- a/drivers/staging/wfx/sta.c
    +++ b/drivers/staging/wfx/sta.c
    @@ -761,17 +761,6 @@ 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;
    @@ -788,12 +777,22 @@ 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
    @@ -825,6 +824,7 @@ 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
    --
    2.27.0


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