linux-kernel - [PATCH 4.19 060/103] netfilter: arp_tables: init netns pointer in xt_tgdtor

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Date:   Wed, 22 Jan 2020 10:29:16 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+91bdd8eece0f6629ec8b@...kaller.appspotmail.com,
        Florian Westphal <fw@...len.de>,
        Pablo Neira Ayuso <pablo@...filter.org>
Subject: [PATCH 4.19 060/103] netfilter: arp_tables: init netns pointer in xt_tgdtor_param struct

From: Florian Westphal <fw@...len.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@...kaller.appspotmail.com
Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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
@@ -495,12 +495,13 @@ 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;
@@ -583,7 +584,7 @@ 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,
@@ -989,7 +990,7 @@ 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;
@@ -1286,7 +1287,7 @@ 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;
@@ -1513,7 +1514,7 @@ 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;
@@ -1525,7 +1526,7 @@ 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);
@@ -1565,7 +1566,7 @@ 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;
 	}
 
@@ -1580,7 +1581,7 @@ 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. */