Subject: Re: [PATCH] ethtool: __ethtool_set_sg: check for function pointer before using it

From: Ben Hutchings <[email-masked]>
Date: Thu, 17 Mar 2011 16:52:13 +0000

On Thu, 2011-03-17 at 17:37 +0100, Roger Luethi wrote:
> __ethtool_set_sg does not check if dev->ethtool_ops->set_sg is defined
> which can result in a NULL pointer dereference when ethtool is used to
> change SG settings for drivers without SG support.
> 
> Signed-off-by: Roger Luethi <[email-masked]>
Reviewed-by: Ben Hutchings <[email-masked]>

Michał, was this just an oversight or is there some reason why we
shouldn't check set_sg immediately?

Ben.

> ---
> 
> Bug verified. Patch only compile-tested.
>
>  net/core/ethtool.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/net/core/ethtool.c b/net/core/ethtool.c
> index c1a71bb..a1086fb 100644
> --- a/net/core/ethtool.c
> +++ b/net/core/ethtool.c
> @@ -1457,6 +1457,9 @@ static int __ethtool_set_sg(struct net_device *dev, u32 data)
>  {
>  	int err;
>  
> +	if (!dev->ethtool_ops->set_sg)
> +		return -EOPNOTSUPP;
> +
>  	if (data && !(dev->features & NETIF_F_ALL_CSUM))
>  		return -EINVAL;
>  

-- 
Ben Hutchings, Senior Software Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.