[PATCH 4.0 02/55] netfilter: nft_rbtree: fix locking

Greg Kroah-Hartman
2015-07-08T08:16:18Z

From: Patrick McHardy <kaber@trash.net>

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

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/net/netfilter/nft_rbtree.c
+++ b/net/netfilter/nft_rbtree.c
@@ -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;
}