Re: [rfc] netfilter: copy less data to the user

[Dan Carpenter <error27@gmail.com>]

On Thu, Jul 15, 2010 at 11:48:09AM +0200, Patrick McHardy wrote:
> Am 14.07.2010 23:04, schrieb Dan Carpenter:
> > Smatch complains that we copy too much data to the user in ebtables.
> > We copied EBT_FUNCTION_MAXNAMELEN (32) characters to the user here, but 
> > "m->u.match->name" has XT_EXTENSION_MAXNAMELEN (29) characters.
> > 
> > I'm not sure if this is a bug where someone got confused with m->u.name
> > which has 32 characters or if this is done for backwards compatability.
> 
> Looking at ebtables.h, ebt_entry_match->name uses
> EBT_FUNCTION_MAXNAMELEN, which is 32 bytes. Where did you get
> XT_EXTENSION_MAXNAMELEN from?
> 

Exactly.  ebt_entry_match->u.name uses EBT_FUNCTION_MAXNAMELEN but this is
from ebt_entry_match->u.match->name which is type struct xt_match.

But it looks like we're exporting struct ebt_match which also uses
EBT_FUNCTION_MAXNAMELEN.  So maybe the fix is to copy ->u.name instead
of ->u.match->name.

regards,
dan carpenter