[NETFILTER]: Fix rcu race in ipt_REDIRECT

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

1 files changed, 10 insertions, 6 deletions

diff --git a/net/ipv4/netfilter/ipt_REDIRECT.c b/net/ipv4/netfilter/ipt_REDIRECT.c
index d2e13447678e..715cb613405c 100644
--- a/net/ipv4/netfilter/ipt_REDIRECT.c
+++ b/net/ipv4/netfilter/ipt_REDIRECT.c
@@ -88,14 +88,18 @@ redirect_target(struct sk_buff **pskb,
                 newdst = htonl(0x7F000001);
         else {
                 struct in_device *indev;
+                struct in_ifaddr *ifa;
 
-                /* Device might not have an associated in_device. */
-                indev = (struct in_device *)(*pskb)->dev->ip_ptr;
-                if (indev == NULL || indev->ifa_list == NULL)
-                        return NF_DROP;
+                newdst = 0;
+                
+                rcu_read_lock();
+                indev = __in_dev_get((*pskb)->dev);
+                if (indev && (ifa = indev->ifa_list))
+                        newdst = ifa->ifa_local;
+                rcu_read_unlock();
 
-                /* Grab first address on interface. */
-                newdst = indev->ifa_list->ifa_local;
+                if (!newdst)
+                        return NF_DROP;
         }
 
         /* Transfer from original range. */