Re: [PATCH 1/2] Bluetooth: L2CAP: Fix accepting connection request for invalid SPSM

[Tedd Ho-Jeong An <tedd.an@linux.intel.com>]

Hi Luiz,

On Mon, 2022-10-31 at 16:10 -0700, Luiz Augusto von Dentz wrote:
> From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> 
> The Bluetooth spec states that the valid range for SPSM is from
> 0x0001-0x00ff so it is invalid to accept values outside of this range:
> 
>   BLUETOOTH CORE SPECIFICATION Version 5.3 | Vol 3, Part A
>   page 1059:
>   Table 4.15: L2CAP_LE_CREDIT_BASED_CONNECTION_REQ SPSM ranges
> 
> CVE: CVE-2022-42896
> CC: stable@vger.kernel.org
> Reported-by: Tamás Koczka <poprdi@google.com>

Reviewed-by: Tedd Ho-Jeong An <tedd.an@intel.com>

> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> ---
>  net/bluetooth/l2cap_core.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> index ef725ed41303..2978a34ea33f 100644
> --- a/net/bluetooth/l2cap_core.c
> +++ b/net/bluetooth/l2cap_core.c
> @@ -5813,6 +5813,19 @@ static int l2cap_le_connect_req(struct l2cap_conn *conn,
>         BT_DBG("psm 0x%2.2x scid 0x%4.4x mtu %u mps %u", __le16_to_cpu(psm),
>                scid, mtu, mps);
>  
> +       /* BLUETOOTH CORE SPECIFICATION Version 5.3 | Vol 3, Part A
> +        * page 1059:
> +        *
> +        * Valid range: 0x0001-0x00ff
> +        *
> +        * Table 4.15: L2CAP_LE_CREDIT_BASED_CONNECTION_REQ SPSM ranges
> +        */
> +       if (!psm || __le16_to_cpu(psm) > L2CAP_PSM_LE_DYN_END) {
> +               result = L2CAP_CR_LE_BAD_PSM;
> +               chan = NULL;
> +               goto response;
> +       }
> +
>         /* Check if we have socket listening on psm */
>         pchan = l2cap_global_chan_by_psm(BT_LISTEN, psm, &conn->hcon->src,
>                                          &conn->hcon->dst, LE_LINK);
> @@ -6001,6 +6014,18 @@ static inline int l2cap_ecred_conn_req(struct l2cap_conn *conn,
>  
>         psm  = req->psm;
>  
> +       /* BLUETOOTH CORE SPECIFICATION Version 5.3 | Vol 3, Part A
> +        * page 1059:
> +        *
> +        * Valid range: 0x0001-0x00ff
> +        *
> +        * Table 4.15: L2CAP_LE_CREDIT_BASED_CONNECTION_REQ SPSM ranges
> +        */
> +       if (!psm || __le16_to_cpu(psm) > L2CAP_PSM_LE_DYN_END) {
> +               result = L2CAP_CR_LE_BAD_PSM;
> +               goto response;
> +       }
> +
>         BT_DBG("psm 0x%2.2x mtu %u mps %u", __le16_to_cpu(psm), mtu, mps);
>  
>         memset(&pdu, 0, sizeof(pdu));

Regards,
Tedd