* Peter Hurley <peter@xxxxxxxxxxxxxxxxxx> [2011-06-07 16:20:41 -0400]:
> From 3a1e7de889253732609efe80cc6cb465c0e8e7d4 Mon Sep 17 00:00:00 2001
> From: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
> Date: Tue, 7 Jun 2011 15:47:47 -0400
> Subject: [PATCH] Bluetooth: l2cap: removed erroneous NULL ACL packet handling
>
> A 0-length ACL continuation-fragment is a valid NULL packet. Remote
> devices can use the FLOW indicator in the ACL packet header to
> flow-control ACL packets without sending a payload.
>
> From the 2.1 spec, Vol 2, Part B, 6.6.2:
> "Real-time flow control shall be carried out at the packet level by
> the link controller via the flow bit in the packet header
> (see Section 6.4.3 on page 110). With the payload flow bit, traffic
> from the remote end can be controlled. It is allowed to generate and
> send an ACL packet with payload length zero irrespective of flow
> status. L2CAP start-fragment and continue-fragment indications
> (LLID=10 and LLID=01) also retain their meaning when the payload
> length is equal to zero (i.e. an empty start fragment shall not be
> sent in the middle of an on-going ACL-U packet transmission).
> It is always safe to send an ACL packet with length=0 and LLID=01."
>
> Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
> ---
> net/bluetooth/l2cap.c | 6 ++++--
> 1 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
> index 675614e..84b8134 100644
> --- a/net/bluetooth/l2cap.c
> +++ b/net/bluetooth/l2cap.c
> @@ -4743,8 +4743,10 @@ static int l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 fl
> BT_DBG("Cont: frag len %d (expecting %d)", skb->len, conn->rx_len);
>
> if (!conn->rx_len) {
> - BT_ERR("Unexpected continuation frame (len %d)", skb->len);
> - l2cap_conn_unreliable(conn, ECOMM);
> + /* A 0-length, continuation fragment is a NULL packet
> + * (Core 2.1, Vol 2, Part B, 6.5.1.2, 6.4.3 & 6.6.2)
> + * The remote device is likely controlling packet flow
> + * with ACL payload header FLOW indicator. */
Then you need to check if it really is zero length, and you also need to
rebase this patch on top bluetooth-next tree.
Gustavo
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