Re: [PATCH nf v2] netfilter/osf: avoid OOB read

[Florian Westphal]

Wander Lairson Costa <wander@xxxxxxxxxx> wrote:
> 
> diff --git a/net/netfilter/nfnetlink_osf.c b/net/netfilter/nfnetlink_osf.c
> index 8f1bfa6ccc2d..13fedf2aaa0f 100644
> --- a/net/netfilter/nfnetlink_osf.c
> +++ b/net/netfilter/nfnetlink_osf.c
> @@ -315,6 +315,9 @@ static int nfnl_osf_add_callback(struct sk_buff *skb,
>  
>  	f = nla_data(osf_attrs[OSF_ATTR_FINGER]);
>  
> +	if (f->opt_num > ARRAY_SIZE(f->opt))
> +		return -EINVAL;
> +

Hmm, this isn't enough; as far as I can see there is no validation
whatsover.

This should also check that all of:

 char    genre[MAXGENRELEN];
 char    version[MAXGENRELEN];
 char    subtype[MAXGENRELEN];

... have a NUL byte.  You could use strnlen() == ARRAY_SIZE() -> EINVAL
for those.

Maybe there is more to be validated, I did not followup with all the
nested structures buried in user_finger struct.