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

[Bartlomiej Zolnierkiewicz]

Acked-by: Bartlomiej Zolnierkiewicz <bartlomiej.zolnierkiewicz at canonical.com>

On Tue, Apr 5, 2022 at 3:41 PM Thadeu Lima de Souza Cascardo
<cascardo at canonical.com> 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);
>
> --
> 2.32.0