[PATCH] Bluetooth: Initialize the TX queue lock when creating struct l2cap_chan in 6LOWPAN

When L2CAP channel is destroyed by hci_unregister_dev, it will
acquire the spin lock of the (struct l2cap_chan *)->tx_q list to
delete all the buffers. But sometimes when hci_unregister_dev is
being called, this lock may have not bee initialized. Initialize
the TX queue lock when creating struct l2cap_chan in 6LOWPAN to fix
this problem.

Reported-by: syzbot+fadfba6a911f6bf71842@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=fadfba6a911f6bf71842
Signed-off-by: Coiby Xu <redacted>
---
 net/bluetooth/6lowpan.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c
index bb55d92691b0..713c618a73df 100644
--- a/net/bluetooth/6lowpan.c
+++ b/net/bluetooth/6lowpan.c

@@ -651,6 +651,7 @@ static struct l2cap_chan *chan_create(void)
 
 	l2cap_chan_set_defaults(chan);
 
+	skb_queue_head_init(&chan->tx_q);
 	chan->chan_type = L2CAP_CHAN_CONN_ORIENTED;
 	chan->mode = L2CAP_MODE_LE_FLOWCTL;
 	chan->imtu = 1280;

-- 
2.27.0

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On Tue, Aug 04, 2020 at 05:39:37PM +0800, Coiby Xu wrote:

Nice, did syzbot verify that this resolves the issue?

thanks,

greg k-h
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On Tue, Aug 04, 2020 at 11:42:53AM +0200, Greg KH wrote:

On Tue, Aug 04, 2020 at 05:39:37PM +0800, Coiby Xu wrote:

quoted

When L2CAP channel is destroyed by hci_unregister_dev, it will
acquire the spin lock of the (struct l2cap_chan *)->tx_q list to
delete all the buffers. But sometimes when hci_unregister_dev is
being called, this lock may have not bee initialized. Initialize
the TX queue lock when creating struct l2cap_chan in 6LOWPAN to fix
this problem.

Reported-by: syzbot+fadfba6a911f6bf71842@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=fadfba6a911f6bf71842
Signed-off-by: Coiby Xu <redacted>
---
 net/bluetooth/6lowpan.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c
index bb55d92691b0..713c618a73df 100644
--- a/net/bluetooth/6lowpan.c
+++ b/net/bluetooth/6lowpan.c

@@ -651,6 +651,7 @@ static struct l2cap_chan *chan_create(void)

 	l2cap_chan_set_defaults(chan);

+	skb_queue_head_init(&chan->tx_q);
 	chan->chan_type = L2CAP_CHAN_CONN_ORIENTED;
 	chan->mode = L2CAP_MODE_LE_FLOWCTL;
 	chan->imtu = 1280;

Nice, did syzbot verify that this resolves the issue?

thanks,

greg k-h

Yes. Thank you for reminding me. I'll also add an Tested-by: tag next time.

--
Best regards,
Coiby
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