netfilter: make it safer during the inet6_dev->addr_list traversal

inet6_dev->addr_list is protected by inet6_dev->lock, so only using
rcu_read_lock is not enough, we should acquire read_lock_bh(&idev->lock)
before the inet6_dev->addr_list traversal.

Signed-off-by: Liping Zhang <zlpnobody@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

2 files changed, 6 insertions, 1 deletions

diff --git a/net/netfilter/nf_nat_redirect.c b/net/netfilter/nf_nat_redirect.c
index d43869879fcf..86067560a318 100644
--- a/net/netfilter/nf_nat_redirect.c
+++ b/net/netfilter/nf_nat_redirect.c
@@ -101,11 +101,13 @@ nf_nat_redirect_ipv6(struct sk_buff *skb, const struct nf_nat_range *range,
                 rcu_read_lock();
                 idev = __in6_dev_get(skb->dev);
                 if (idev != NULL) {
+                        read_lock_bh(&idev->lock);
                         list_for_each_entry(ifa, &idev->addr_list, if_list) {
                                 newdst = ifa->addr;
                                 addr = true;
                                 break;
                         }
+                        read_unlock_bh(&idev->lock);
                 }
                 rcu_read_unlock();
 
diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
index 80cb7babeb64..df7f1df00330 100644
--- a/net/netfilter/xt_TPROXY.c
+++ b/net/netfilter/xt_TPROXY.c
@@ -393,7 +393,8 @@ tproxy_laddr6(struct sk_buff *skb, const struct in6_addr *user_laddr,
 
         rcu_read_lock();
         indev = __in6_dev_get(skb->dev);
-        if (indev)
+        if (indev) {
+                read_lock_bh(&indev->lock);
                 list_for_each_entry(ifa, &indev->addr_list, if_list) {
                         if (ifa->flags & (IFA_F_TENTATIVE | IFA_F_DEPRECATED))
                                 continue;
@@ -401,6 +402,8 @@ tproxy_laddr6(struct sk_buff *skb, const struct in6_addr *user_laddr,
                         laddr = &ifa->addr;
                         break;
                 }
+                read_unlock_bh(&indev->lock);
+        }
         rcu_read_unlock();
 
         return laddr ? laddr : daddr;