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From: Marcel Holtmann <marcel@holtmann.org>
To: Coiby Xu <coiby.xu@gmail.com>
Cc: syzbot+dd768a260f7358adbaf9@syzkaller.appspotmail.com,
	Johan Hedberg <johan.hedberg@gmail.com>,
	syzkaller-bugs@googlegroups.com,
	open list <linux-kernel@vger.kernel.org>,
	linux-bluetooth <linux-bluetooth@vger.kernel.org>,
	"open list:NETWORKING \[GENERAL\]" <netdev@vger.kernel.org>,
	Jakub Kicinski <kuba@kernel.org>,
	linux-kernel-mentees@lists.linuxfoundation.org,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [Linux-kernel-mentees] [PATCH] Bluetooth: fix "list_add double add" in hci_conn_complete_evt
Date: Mon, 31 Aug 2020 18:06:18 +0200	[thread overview]
Message-ID: <C0A907BA-9C0D-4124-A2AF-3748055DB062@holtmann.org> (raw)
In-Reply-To: <20200823010022.938532-1-coiby.xu@gmail.com>

Hi Coiby,

> When two HCI_EV_CONN_COMPLETE event packets with status=0 of the same
> HCI connection are received, device_add would be called twice which
> leads to kobject_add being called twice. Thus duplicate
> (struct hci_conn *conn)->dev.kobj.entry would be inserted into
> (struct hci_conn *conn)->dev.kobj.kset->list.
> 
> This issue can be fixed by checking (struct hci_conn *conn)->debugfs.
> If it's not NULL, it means the HCI connection has been completed and we
> won't duplicate the work as for processing the first
> HCI_EV_CONN_COMPLETE event.

do you have a btmon trace for this happening?

> Reported-and-tested-by: syzbot+dd768a260f7358adbaf9@syzkaller.appspotmail.com
> Link: https://syzkaller.appspot.com/bug?extid=dd768a260f7358adbaf9
> Signed-off-by: Coiby Xu <coiby.xu@gmail.com>
> ---
> net/bluetooth/hci_event.c | 5 +++++
> 1 file changed, 5 insertions(+)
> 
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 4b7fc430793c..1233739ce760 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -2605,6 +2605,11 @@ static void hci_conn_complete_evt(struct hci_dev *hdev, struct sk_buff *skb)
> 	}
> 
> 	if (!ev->status) {
> +		if (conn->debugfs) {
> +			bt_dev_err(hdev, "The connection has been completed");
> +			goto unlock;
> +		}
> +

And instead of doing papering over a hole, I would rather detect that the HCI event is not valid since we already received one for this connection.

Regards

Marcel

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  reply	other threads:[~2020-08-31 16:06 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <000000000000c57f2d05ac4c5b8e@google.com>
2020-08-20  6:07 ` [Linux-kernel-mentees] BUG: corrupted list in kobject_add_internal Coiby Xu
2020-08-20  6:13   ` Dmitry Vyukov via Linux-kernel-mentees
2020-08-22 16:16     ` Coiby Xu
2020-08-23  1:00 ` [Linux-kernel-mentees] [PATCH] Bluetooth: fix "list_add double add" in hci_conn_complete_evt Coiby Xu
2020-08-31 16:06   ` Marcel Holtmann [this message]
2020-09-02 12:31     ` Coiby Xu
2020-11-08 22:55 ` [Linux-kernel-mentees] BUG: corrupted list in kobject_add_internal syzbot
2020-11-11 11:22   ` Dmitry Vyukov via Linux-kernel-mentees

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