Subject: Re: iptables: ensure number of counters is >0 in do_replace()

From: Dave Jones <[email-masked]>
Date: Tue, 19 May 2015 19:42:52 -0400

On Wed, May 20, 2015 at 01:19:50AM +0200, Florian Westphal wrote:
 > Dave Jones <[email-masked]> wrote:
 > > After improving setsockopt() coverage in trinity, I started triggering
 > > vmalloc failures pretty reliably from this code path:
 > > 
 > > warn_alloc_failed+0xe9/0x140
 > > __vmalloc_node_range+0x1be/0x270
 > > vzalloc+0x4b/0x50
 > > __do_replace+0x52/0x260 [ip_tables]
 > > do_ipt_set_ctl+0x15d/0x1d0 [ip_tables]
 > > nf_setsockopt+0x65/0x90
 > > ip_setsockopt+0x61/0xa0
 > > raw_setsockopt+0x16/0x60
 > > sock_common_setsockopt+0x14/0x20
 > > SyS_setsockopt+0x71/0xd0
 > > 
 > > It turns out we don't validate that the num_counters field in the
 > > struct we pass in from userspace is initialized.
 > > 
 > > Signed-off-by: Dave Jones <[email-masked]>
 > > 
 > > diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
 > > index c69db7fa25ee..12a33d178614 100644
 > > --- a/net/ipv4/netfilter/ip_tables.c
 > > +++ b/net/ipv4/netfilter/ip_tables.c
 > > @@ -1262,6 +1262,9 @@ do_replace(struct net *net, const void __user *user, unsigned int len)
 > >  	/* overflow check */
 > >  	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 > >  		return -ENOMEM;
 > > +	if (tmp.num_counters == 0)
 > > +		return -EINVAL;
 > > +
 > 
 > Good catch.  Due to iptables wonderful copy-paste programming model,
 > this also needs fixing in compat_do_replace, ip6tables, arbtables and
 > ebtables (8 different places, ick).

ugh. ok, I'll fix them all up.
What's the preferred format, 8 separate patches, or 1 all-in-one diff
for all instances of this bug ?

thanks,

	Dave