[SRU Kinetic 1/2] Bluetooth: L2CAP: Fix accepting connection request for invalid SPSM

[Thadeu Lima de Souza Cascardo]

On Fri, Dec 02, 2022 at 09:10:16PM +0300, Cengiz Can wrote:
> From: Luiz Augusto von Dentz <luiz.von.dentz at 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 at vger.kernel.org
> Reported-by: Tamás Koczka <poprdi at google.com>
> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz at intel.com>
> Reviewed-by: Tedd Ho-Jeong An <tedd.an at intel.com>
> (cherry picked from commit 711f8c3fb3db61897080468586b970c87c61d9e4)

You still need the CVE line here. I don't think our changelog machinery
understands the line above.

Cascardo.

> Signed-off-by: Cengiz Can <cengiz.can at canonical.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 0fc30664249b..375ab8fa3bcf 100644
> --- a/net/bluetooth/l2cap_core.c
> +++ b/net/bluetooth/l2cap_core.c
> @@ -5812,6 +5812,19 @@ 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);
> @@ -6000,6 +6013,18 @@ 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));
> -- 
> 2.37.2
> 
> 
> -- 
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