Patch "netfilter: nft_rbtree: fix locking" has been added to the 4.0-stable tree

This is a note to let you know that I've just added the patch titled

netfilter: nft_rbtree: fix locking

to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
netfilter-nft_rbtree-fix-locking.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Patrick McHardy <[email protected]>
Date: Sat, 21 Mar 2015 15:19:14 +0000
Subject: netfilter: nft_rbtree: fix locking

From: Patrick McHardy <[email protected]>

commit 16c45eda96038aae848b6cfd42e2bf4b5e80f365 upstream.

Fix a race condition and unnecessary locking:

* the root rb_node must only be accessed under the lock in nft_rbtree_lookup()
* the lock is not needed in lookup functions in netlink context

---
 net/netfilter/nft_rbtree.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

@@ -37,10 +37,11 @@ static bool nft_rbtree_lookup(const stru
 {
 	const struct nft_rbtree *priv = nft_set_priv(set);
 	const struct nft_rbtree_elem *rbe, *interval = NULL;
-	const struct rb_node *parent = priv->root.rb_node;
+	const struct rb_node *parent;
 	int d;
 
 	spin_lock_bh(&nft_rbtree_lock);
+	parent = priv->root.rb_node;
 	while (parent != NULL) {
 		rbe = rb_entry(parent, struct nft_rbtree_elem, node);
 

@@ -158,7 +159,6 @@ static int nft_rbtree_get(const struct n
 	struct nft_rbtree_elem *rbe;
 	int d;
 
-	spin_lock_bh(&nft_rbtree_lock);
 	while (parent != NULL) {
 		rbe = rb_entry(parent, struct nft_rbtree_elem, node);
 

@@ -173,11 +173,9 @@ static int nft_rbtree_get(const struct n
 			    !(rbe->flags & NFT_SET_ELEM_INTERVAL_END))
 				nft_data_copy(&elem->data, rbe->data);
 			elem->flags = rbe->flags;
-			spin_unlock_bh(&nft_rbtree_lock);
 			return 0;
 		}
 	}
-	spin_unlock_bh(&nft_rbtree_lock);
 	return -ENOENT;
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.0/netfilter-nft_rbtree-fix-locking.patch