Re: [patch 2/2 v2] staging: lustre: integer overflow in obd_ioctl_is_invalid()

[walter harms]

Am 28.04.2014 12:58, schrieb Dan Carpenter:
> The obd_ioctl_getdata() function caps "data->ioc_len" at
> OBD_MAX_IOCTL_BUFFER and then calls this obd_ioctl_is_invalid() to check
> that the other values inside data are valid.
> 
> There are several lengths inside data but when they are added together
> they must not be larger than "data->ioc_len".  The checks against
> "(data->ioc_inllen1 > (1<<30))" are supposed to ensure that the addition
> does not have an integer overflow.  But "(1<<30) * 4" actually can
> overflow 32 bits, so the checks are insufficient.
> 
> I have changed it to "> OBD_MAX_IOCTL_BUFFER" instead.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
> v2: Updated the error messages as Walter Harms pointed out.
> 
> diff --git a/drivers/staging/lustre/lustre/include/lustre_lib.h b/drivers/staging/lustre/lustre/include/lustre_lib.h
> index bdc9812..3c26bbd 100644
> --- a/drivers/staging/lustre/lustre/include/lustre_lib.h
> +++ b/drivers/staging/lustre/lustre/include/lustre_lib.h
> @@ -179,24 +179,25 @@ static inline int obd_ioctl_packlen(struct obd_ioctl_data *data)
>  
>  static inline int obd_ioctl_is_invalid(struct obd_ioctl_data *data)
>  {
> -	if (data->ioc_len > (1<<30)) {
> -		CERROR("OBD ioctl: ioc_len larger than 1<<30\n");
> +	if (data->ioc_len > OBD_MAX_IOCTL_BUFFER) {
> +		CERROR("OBD ioctl: ioc_len larger than %d\n",
> +		       OBD_MAX_IOCTL_BUFFER);
>  		return 1;
>  	}
> -	if (data->ioc_inllen1 > (1<<30)) {
> -		CERROR("OBD ioctl: ioc_inllen1 larger than 1<<30\n");
> +	if (data->ioc_inllen1 > OBD_MAX_IOCTL_BUFFER) {
> +		CERROR("OBD ioctl: ioc_inllen1 larger than ioc_len\n");
>  		return 1;
>  	}

The error mention ioc_len the compare is OBD_MAX_IOCTL_BUFFER ?
Is that intentional ?

re,
 wh

> -	if (data->ioc_inllen2 > (1<<30)) {
> -		CERROR("OBD ioctl: ioc_inllen2 larger than 1<<30\n");
> +	if (data->ioc_inllen2 > OBD_MAX_IOCTL_BUFFER) {
> +		CERROR("OBD ioctl: ioc_inllen2 larger than ioc_len\n");
>  		return 1;
>  	}
> -	if (data->ioc_inllen3 > (1<<30)) {
> -		CERROR("OBD ioctl: ioc_inllen3 larger than 1<<30\n");
> +	if (data->ioc_inllen3 > OBD_MAX_IOCTL_BUFFER) {
> +		CERROR("OBD ioctl: ioc_inllen3 larger than ioc_len\n");
>  		return 1;
>  	}
> -	if (data->ioc_inllen4 > (1<<30)) {
> -		CERROR("OBD ioctl: ioc_inllen4 larger than 1<<30\n");
> +	if (data->ioc_inllen4 > OBD_MAX_IOCTL_BUFFER) {
> +		CERROR("OBD ioctl: ioc_inllen4 larger than ioc_len\n");
>  		return 1;
>  	}
>  	if (data->ioc_inlbuf1 && !data->ioc_inllen1) {
> 
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