Re: [RESEND][PATCH 4/4] NFC: fdp: Fix possible buffer overflow in WCS4000 NFC driver

[Greg KH]

On Wed, Apr 18, 2018 at 03:35:04PM +0530, Amit Pundir wrote:
> From: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> 
> Possible buffer overflow when reading next_read_size bytes into
> tmp buffer after next_read_size was extracted from a previous packet.
> 
> Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> Signed-off-by: Amit Pundir <amit.pundir@xxxxxxxxxx>
> ---
>  drivers/nfc/fdp/i2c.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/nfc/fdp/i2c.c b/drivers/nfc/fdp/i2c.c
> index c4da50e07bbc..08a4f82a2965 100644
> --- a/drivers/nfc/fdp/i2c.c
> +++ b/drivers/nfc/fdp/i2c.c
> @@ -176,6 +176,16 @@ static int fdp_nci_i2c_read(struct fdp_i2c_phy *phy, struct sk_buff **skb)
>  		/* Packet that contains a length */
>  		if (tmp[0] == 0 && tmp[1] == 0) {
>  			phy->next_read_size = (tmp[2] << 8) + tmp[3] + 3;
> +			/*
> +			 * Ensure next_read_size does not exceed sizeof(tmp)
> +			 * for reading that many bytes during next iteration
> +			 */
> +			if (phy->next_read_size > FDP_NCI_I2C_MAX_PAYLOAD) {
> +				dev_dbg(&client->dev, "%s: corrupted packet\n",
> +					__func__);

As Andy points out, no need for __func__ in any dev_dbg() call.

thanks,

greg k-h