[PATCH] Bluetooth: Fix ERTM L2CAP resend packet

[PATCH] Bluetooth: Fix ERTM L2CAP resend packet

[Lukasz Rymanowski]

I-Frame which is going to be resend already has FCS field added and set
(if it was required). Adding additional FCS field calculated from data +
old FCS in resend function is incorrect.

This patch fix that.

Cached on PTS testing.

Signed-off-by: Lukasz Rymanowski <lukasz.rymanowski@tieto.com>
---
 net/bluetooth/l2cap_core.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 0cd7ed9..7b0d744 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -1968,10 +1968,11 @@ static void l2cap_ertm_resend(struct l2cap_chan *chan)
 					   tx_skb->data + L2CAP_HDR_SIZE);
 		}
 
+		/* Update FCS */
 		if (chan->fcs == L2CAP_FCS_CRC16) {
-			u16 fcs = crc16(0, (u8 *) tx_skb->data, tx_skb->len);
-			put_unaligned_le16(fcs, skb_put(tx_skb,
-							L2CAP_FCS_SIZE));
+			u16 fcs = crc16(0, (u8 *)tx_skb->data, tx_skb->len -
+					L2CAP_FCS_SIZE);
+			put_unaligned_le16(fcs, tx_skb->tail - L2CAP_FCS_SIZE);
 		}
 
 		l2cap_do_send(chan, tx_skb);
-- 
1.8.4

Re: [PATCH] Bluetooth: Fix ERTM L2CAP resend packet

[Marcel Holtmann]

Hi Lukasz,

> I-Frame which is going to be resend already has FCS field added and set
> (if it was required). Adding additional FCS field calculated from data +
> old FCS in resend function is incorrect.
> 
> This patch fix that.
> 
> Cached on PTS testing.

"Issue has been found during PTS testing."

No caching ;)

> 
> Signed-off-by: Lukasz Rymanowski <lukasz.rymanowski@tieto.com>
> ---
> net/bluetooth/l2cap_core.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> index 0cd7ed9..7b0d744 100644
> --- a/net/bluetooth/l2cap_core.c
> +++ b/net/bluetooth/l2cap_core.c
> @@ -1968,10 +1968,11 @@ static void l2cap_ertm_resend(struct l2cap_chan *chan)
> 					   tx_skb->data + L2CAP_HDR_SIZE);
> 		}
> 
> +		/* Update FCS */
> 		if (chan->fcs == L2CAP_FCS_CRC16) {
> -			u16 fcs = crc16(0, (u8 *) tx_skb->data, tx_skb->len);
> -			put_unaligned_le16(fcs, skb_put(tx_skb,
> -							L2CAP_FCS_SIZE));
> +			u16 fcs = crc16(0, (u8 *)tx_skb->data, tx_skb->len -
> +					L2CAP_FCS_SIZE);

+                       u16 fcs = crc16(0, (u8 *) tx_skb->data,
+                                       tx_skb->len - L2CAP_FCS_SIZE);

> +			put_unaligned_le16(fcs, tx_skb->tail - L2CAP_FCS_SIZE);
> 		}

  CC      net/bluetooth/l2cap_core.o
net/bluetooth/l2cap_core.c: In function ‘l2cap_ertm_resend’:
net/bluetooth/l2cap_core.c:1975:4: warning: passing argument 2 of ‘put_unaligned_le16’ makes pointer from integer without a cast [enabled by default]
    put_unaligned_le16(fcs, tx_skb->tail - L2CAP_FCS_SIZE);
    ^
In file included from ./arch/x86/include/asm/unaligned.h:8:0,
                 from include/net/bluetooth/l2cap.h:30,
                 from net/bluetooth/l2cap_core.c:38:
include/linux/unaligned/access_ok.h:37:91: note: expected ‘void *’ but argument is of type ‘sk_buff_data_t’  static inline void put_unaligned_le16(u16 val, void *p)
                                                                                           ^

Regards

Marcel