[Devel] Re: [PATCH] iptables compat code error way & module refcounting fix

[Dmitry Mishin]

On Monday 30 October 2006 18:45, Patrick McHardy wrote:
> Dmitry Mishin wrote:
> > This patch fixes bug in iptables modules refcounting on compat error way.
> >
> > As we are getting modules in check_compat_entry_size_and_hooks(), in case
> > of later error, we should put them all in translate_compat_table(), not 
> > in the compat_copy_entry_from_user() or compat_copy_match_from_user(), as
> > it is now.
> >
> > Signed-off-by: Dmitry Mishin <dim at openvz.org>
> > Acked-by: Vasily Averin <vvs at openvz.org>
> > Acked-by: Kirill Korotaev <dev at openvz.org>
> >
> >  ip_tables.c |   36 +++++++++++-------------------------
> >  1 file changed, 11 insertions(+), 25 deletions(-)
> >
> > ----
> > @@ -1618,7 +1603,7 @@ translate_compat_table(const char *name,
> >  		unsigned int *hook_entries,
> >  		unsigned int *underflows)
> >  {
> > -	unsigned int i;
> > +	unsigned int i, j;
> >  	struct xt_table_info *newinfo, *info;
> >  	void *pos, *entry0, *entry1;
> >  	unsigned int size;
> > @@ -1636,21 +1621,21 @@ translate_compat_table(const char *name,
> >  	}
> >
> >  	duprintf("translate_compat_table: size %u\n", info->size);
> > -	i = 0;
> > +	j = 0;
> >  	xt_compat_lock(AF_INET);
> >  	/* Walk through entries, checking offsets. */
> >  	ret = IPT_ENTRY_ITERATE(entry0, total_size,
> >  				check_compat_entry_size_and_hooks,
> >  				info, &size, entry0,
> >  				entry0 + total_size,
> > -				hook_entries, underflows, &i, name);
> > +				hook_entries, underflows, &j, name);
> >  	if (ret != 0)
> >  		goto out_unlock;
> >
> >  	ret = -EINVAL;
> > -	if (i != number) {
> > +	if (j != number) {
> >  		duprintf("translate_compat_table: %u not %u entries\n",
> > -			 i, number);
> > +			 j, number);
> >  		goto out_unlock;
> >  	}
> >
> > @@ -1709,6 +1694,7 @@ translate_compat_table(const char *name,
> >  free_newinfo:
> >  	xt_free_table_info(newinfo);
> >  out:
> > +	IPT_ENTRY_ITERATE(entry0, total_size, cleanup_entry, &j);
> >  	return ret;
> >  out_unlock:
> >  	xt_compat_unlock(AF_INET);
>
> This doesn't look right, if we fail at xt_alloc_table_info for
> example the module references are not released.
module references will be released because of 'goto out;' line just after 
xt_compat_unlock() - it is missed because of standard +-3 lines patch 
context, sorry.

-- 
Thanks,
Dmitry.