Re: [PATCH] Bluetooth: Fix locking of hdev when calling into SMP code

[Lukasz Rymanowski <lukasz.rymanowski@gmail.com>]

Hi Johan,

On Fri, Jun 13, 2014 at 9:22 AM,  <johan.hedberg@gmail.com> wrote:
> From: Johan Hedberg <johan.hedberg@intel.com>
>
> The SMP code expects hdev to be unlocked since e.g. crypto functions
> will try to (re)lock it. Therefore, we need to release the lock before
> calling into smp.c from mgmt.c. Without this we risk a deadlock whenever
> the smp_user_confirm_reply() function is called.
>
> Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
> ---
>  net/bluetooth/mgmt.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
> index 6107e037cd8e..af8e0a6243b7 100644
> --- a/net/bluetooth/mgmt.c
> +++ b/net/bluetooth/mgmt.c
> @@ -3031,8 +3031,13 @@ static int user_pairing_resp(struct sock *sk, struct hci_dev *hdev,
>         }
>
>         if (addr->type == BDADDR_LE_PUBLIC || addr->type == BDADDR_LE_RANDOM) {
> -               /* Continue with pairing via SMP */
> +               /* Continue with pairing via SMP. The hdev lock must be
> +                * released as SMP may try to recquire it for crypto
> +                * purposes.
> +                */
> +               hci_dev_unlock(hdev);
>                 err = smp_user_confirm_reply(conn, mgmt_op, passkey);
> +               hci_dev_lock(hdev);
>
>                 if (!err)
>                         err = cmd_complete(sk, hdev->id, mgmt_op,
> --
> 1.9.3

Works fine.

Tested-by: Lukasz Rymanowski <lukasz.rymanowski@tieto.com>

BR
\Łukasz
>
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