ACK: [SRU Bionic/Focal/Impish/Jammy] nfc: st21nfca: Fix potential buffer overflows in EVT_TRANSACTION

[Tim Gardner]

Acked-by: Tim Gardner <tim.gardner at canonical.com>

On 4/5/22 07:40, Thadeu Lima de Souza Cascardo wrote:
> From: Jordy Zomer <jordy at pwning.systems>
> 
> It appears that there are some buffer overflows in EVT_TRANSACTION.
> This happens because the length parameters that are passed to memcpy
> come directly from skb->data and are not guarded in any way.
> 
> Signed-off-by: Jordy Zomer <jordy at pwning.systems>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski at canonical.com>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> (cherry picked from commit 4fbcc1a4cb20fe26ad0225679c536c80f1648221)
> CVE-2022-26490
> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo at canonical.com>
> ---
>   drivers/nfc/st21nfca/se.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/nfc/st21nfca/se.c b/drivers/nfc/st21nfca/se.c
> index c8bdf078d111..0841e0e370a0 100644
> --- a/drivers/nfc/st21nfca/se.c
> +++ b/drivers/nfc/st21nfca/se.c
> @@ -320,6 +320,11 @@ int st21nfca_connectivity_event_received(struct nfc_hci_dev *hdev, u8 host,
>   			return -ENOMEM;
>   
>   		transaction->aid_len = skb->data[1];
> +
> +		/* Checking if the length of the AID is valid */
> +		if (transaction->aid_len > sizeof(transaction->aid))
> +			return -EINVAL;
> +
>   		memcpy(transaction->aid, &skb->data[2],
>   		       transaction->aid_len);
>   
> @@ -329,6 +334,11 @@ int st21nfca_connectivity_event_received(struct nfc_hci_dev *hdev, u8 host,
>   			return -EPROTO;
>   
>   		transaction->params_len = skb->data[transaction->aid_len + 3];
> +
> +		/* Total size is allocated (skb->len - 2) minus fixed array members */
> +		if (transaction->params_len > ((skb->len - 2) - sizeof(struct nfc_evt_transaction)))
> +			return -EINVAL;
> +
>   		memcpy(transaction->params, skb->data +
>   		       transaction->aid_len + 4, transaction->params_len);
>   

-- 
-----------
Tim Gardner
Canonical, Inc