[PATCH 3.16 179/245] netfilter: arp_tables: init netns pointer in xt_tgdtor_param struct

Ben Hutchings
2020-04-23T23:11:05Z

From: Florian Westphal <fw@strlen.de>

commit 212e7f56605ef9688d0846db60c6c6ec06544095 upstream.

An earlier commit (1b789577f655060d98d20e,
"netfilter: arp_tables: init netns pointer in xt_tgchk_param struct")
fixed missing net initialization for arptables, but turns out it was
incomplete. We can get a very similar struct net NULL deref during
error unwinding:

general protection fault: 0000 [#1] PREEMPT SMP KASAN
RIP: 0010:xt_rateest_put+0xa1/0x440 net/netfilter/xt_RATEEST.c:77
xt_rateest_tg_destroy+0x72/0xa0 net/netfilter/xt_RATEEST.c:175
cleanup_entry net/ipv4/netfilter/arp_tables.c:509 [inline]
translate_table+0x11f4/0x1d80 net/ipv4/netfilter/arp_tables.c:587
do_replace net/ipv4/netfilter/arp_tables.c:981 [inline]
do_arpt_set_ctl+0x317/0x650 net/ipv4/netfilter/arp_tables.c:1461

Also init the netns pointer in xt_tgdtor_param struct.

Fixes: add67461240c1d ("netfilter: add struct net * to target parameters")
Reported-by: syzbot+91bdd8eece0f6629ec8b@syzkaller.appspotmail.com
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
[bwh: Backported to 3.16:
- __arpt_unregister_table() has not been split out of
arpt_unregister_table()
- Add "net" parameter to arpt_unregister_table() and update its only
caller in arptable_filter.c]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
--- a/include/linux/netfilter_arp/arp_tables.h
+++ b/include/linux/netfilter_arp/arp_tables.h
@@ -51,7 +51,7 @@ extern void *arpt_alloc_initial_table(co
extern struct xt_table *arpt_register_table(struct net *net,
const struct xt_table *table,
const struct arpt_replace *repl);
-extern void arpt_unregister_table(struct xt_table *table);
+extern void arpt_unregister_table(struct net *, struct xt_table *table);
extern unsigned int arpt_do_table(struct sk_buff *skb,
unsigned int hook,
const struct net_device *in,
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -602,12 +602,13 @@ static inline int check_entry_size_and_h
return 0;
}

-static inline void cleanup_entry(struct arpt_entry *e)
+static void cleanup_entry(struct arpt_entry *e, struct net *net)
{
struct xt_tgdtor_param par;
struct xt_entry_target *t;

t = arpt_get_target(e);
+ par.net = net;
par.target = t->u.kernel.target;
par.targinfo = t->data;
par.family = NFPROTO_ARP;
@@ -706,7 +707,7 @@ static int translate_table(struct net *n
xt_entry_foreach(iter, entry0, newinfo->size) {
if (i-- == 0)
break;
- cleanup_entry(iter);
+ cleanup_entry(iter, net);
}
return ret;
}
@@ -1051,7 +1052,7 @@ static int __do_replace(struct net *net,
/* Decrease module usage counts and free resource */
loc_cpu_old_entry = oldinfo->entries[raw_smp_processor_id()];
xt_entry_foreach(iter, loc_cpu_old_entry, oldinfo->size)
- cleanup_entry(iter);
+ cleanup_entry(iter, net);

xt_free_table_info(oldinfo);
if (copy_to_user(counters_ptr, counters,
@@ -1118,7 +1119,7 @@ static int do_replace(struct net *net, c

free_newinfo_untrans:
xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
- cleanup_entry(iter);
+ cleanup_entry(iter, net);
free_newinfo:
xt_free_table_info(newinfo);
return ret;
@@ -1431,7 +1432,7 @@ static int compat_do_replace(struct net

free_newinfo_untrans:
xt_entry_foreach(iter, loc_cpu_entry, newinfo->size)
- cleanup_entry(iter);
+ cleanup_entry(iter, net);
free_newinfo:
xt_free_table_info(newinfo);
return ret;
@@ -1708,7 +1709,7 @@ out:
return ERR_PTR(ret);
}

-void arpt_unregister_table(struct xt_table *table)
+void arpt_unregister_table(struct net *net, struct xt_table *table)
{
struct xt_table_info *private;
void *loc_cpu_entry;
@@ -1720,7 +1721,7 @@ void arpt_unregister_table(struct xt_tab
/* Decrease module usage counts and free resources */
loc_cpu_entry = private->entries[raw_smp_processor_id()];
xt_entry_foreach(iter, loc_cpu_entry, private->size)
- cleanup_entry(iter);
+ cleanup_entry(iter, net);
if (private->number > private->initial_entries)
module_put(table_owner);
xt_free_table_info(private);
--- a/net/ipv4/netfilter/arptable_filter.c
+++ b/net/ipv4/netfilter/arptable_filter.c
@@ -54,7 +54,7 @@ static int __net_init arptable_filter_ne

static void __net_exit arptable_filter_net_exit(struct net *net)
{
- arpt_unregister_table(net->ipv4.arptable_filter);
+ arpt_unregister_table(net, net->ipv4.arptable_filter);
}

static struct pernet_operations arptable_filter_net_ops = {