[PATCH 4.14 38/65] netfilter: arp_tables: init netns pointer in xt_tgdtor_param struct

Greg Kroah-Hartman
2020-01-22T09:50:16Z

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/ipv4/netfilter/arp_tables.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -506,12 +506,13 @@ 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;
@@ -601,7 +602,7 @@ 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;
}
@@ -926,7 +927,7 @@ static int __do_replace(struct net *net,
/* Decrease module usage counts and free resource */
loc_cpu_old_entry = oldinfo->entries;
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,
@@ -990,7 +991,7 @@ 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;
@@ -1287,7 +1288,7 @@ 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;
@@ -1514,7 +1515,7 @@ static int do_arpt_get_ctl(struct sock *
return ret;
}

-static void __arpt_unregister_table(struct xt_table *table)
+static void __arpt_unregister_table(struct net *net, struct xt_table *table)
{
struct xt_table_info *private;
void *loc_cpu_entry;
@@ -1526,7 +1527,7 @@ static void __arpt_unregister_table(stru
/* Decrease module usage counts and free resources */
loc_cpu_entry = private->entries;
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);
@@ -1566,7 +1567,7 @@ int arpt_register_table(struct net *net,

ret = nf_register_net_hooks(net, ops, hweight32(table->valid_hooks));
if (ret != 0) {
- __arpt_unregister_table(new_table);
+ __arpt_unregister_table(net, new_table);
*res = NULL;
}

@@ -1581,7 +1582,7 @@ void arpt_unregister_table(struct net *n
const struct nf_hook_ops *ops)
{
nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks));
- __arpt_unregister_table(table);
+ __arpt_unregister_table(net, table);
}

/* The built-in targets: standard (NULL) and error. */