Subject: Re: [PATCH] ethtool: fix a kernel infoleak in ethtool_get_pauseparam

From: Ben Hutchings <[email-masked]>
Date: Wed, 01 Jun 2016 18:14:24 +0100

On Wed, 2016-06-01 at 16:39 +0200, Kangjie Lu wrote:
> The field autoneg of pauseparam is not initialized in some
> implementations of get_pauseparam(),

Nonsense.  The current implementation initialises all fields.  (If
there was padding in the structure, this change would be needed to
guarantee that the padding was initialised.  But there isn't.)

Ben.

>  but the whole object is
> copied to userland.
> 
> Signed-off-by: Kangjie Lu <[email-masked]>
> ---
>  net/core/ethtool.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/net/core/ethtool.c b/net/core/ethtool.c
> index f426c5a..84544bd 100644
> --- a/net/core/ethtool.c
> +++ b/net/core/ethtool.c
> @@ -1723,7 +1723,10 @@ static noinline_for_stack int
> ethtool_set_channels(struct net_device *dev,
>  
>  static int ethtool_get_pauseparam(struct net_device *dev, void
> __user *useraddr)
>  {
> -	struct ethtool_pauseparam pauseparam = { ETHTOOL_GPAUSEPARAM
> };
> +	struct ethtool_pauseparam pauseparam;
> +
> +	memset(&pauseparam, 0, sizeof(pauseparam));
> +	pauseparam.cmd = ETHTOOL_GPAUSEPARAM;
>  
>  	if (!dev->ethtool_ops->get_pauseparam)
>  		return -EOPNOTSUPP;
-- 
Ben Hutchings
To err is human; to really foul things up requires a computer.