[NETFILTER]: arp_tables: fix table locking in arpt_do_table

table->private might change because of ruleset changes, don't use it
without holding the lock.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index df4854cf598b..8d1d7a6e72a5 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -236,7 +236,7 @@ unsigned int arpt_do_table(struct sk_buff **pskb,
         struct arpt_entry *e, *back;
         const char *indev, *outdev;
         void *table_base;
-        struct xt_table_info *private = table->private;
+        struct xt_table_info *private;
 
         /* ARP header, plus 2 device addresses, plus 2 IP addresses.  */
         if (!pskb_may_pull((*pskb), (sizeof(struct arphdr) +
@@ -248,6 +248,7 @@ unsigned int arpt_do_table(struct sk_buff **pskb,
         outdev = out ? out->name : nulldevname;
 
         read_lock_bh(&table->lock);
+        private = table->private;
         table_base = (void *)private->entries[smp_processor_id()];
         e = get_entry(table_base, private->hook_entry[hook]);
         back = get_entry(table_base, private->underflow[hook]);