From: Patrick McHardy Date: Mon, 24 Nov 2008 23:56:17 +0000 (-0800) Subject: netfilter: ctnetlink: fix conntrack creation race X-Git-Tag: v2.6.28-rc8~73^2~15 X-Git-Url: http://ftp.safe.ca/?p=safe%2Fjmp%2Flinux-2.6;a=commitdiff_plain;h=b54ad409fd09a395b839fb81f300880d76861c0e netfilter: ctnetlink: fix conntrack creation race Conntrack creation through ctnetlink has two races: - the timer may expire and free the conntrack concurrently, causing an invalid memory access when attempting to put it in the hash tables - an identical conntrack entry may be created in the packet processing path in the time between the lookup and hash insertion Hold the conntrack lock between the lookup and insertion to avoid this. Reported-by: Zoltan Borbely Signed-off-by: Patrick McHardy Signed-off-by: David S. Miller --- diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 622d7c6..233fdd2 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -305,9 +305,7 @@ void nf_conntrack_hash_insert(struct nf_conn *ct) hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); repl_hash = hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); - spin_lock_bh(&nf_conntrack_lock); __nf_conntrack_hash_insert(ct, hash, repl_hash); - spin_unlock_bh(&nf_conntrack_lock); } EXPORT_SYMBOL_GPL(nf_conntrack_hash_insert); diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index a040d46..3b009a3 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -1090,7 +1090,7 @@ ctnetlink_create_conntrack(struct nlattr *cda[], struct nf_conn_help *help; struct nf_conntrack_helper *helper; - ct = nf_conntrack_alloc(&init_net, otuple, rtuple, GFP_KERNEL); + ct = nf_conntrack_alloc(&init_net, otuple, rtuple, GFP_ATOMIC); if (ct == NULL || IS_ERR(ct)) return -ENOMEM; @@ -1212,13 +1212,14 @@ ctnetlink_new_conntrack(struct sock *ctnl, struct sk_buff *skb, atomic_inc(&master_ct->ct_general.use); } - spin_unlock_bh(&nf_conntrack_lock); err = -ENOENT; if (nlh->nlmsg_flags & NLM_F_CREATE) err = ctnetlink_create_conntrack(cda, &otuple, &rtuple, master_ct); + spin_unlock_bh(&nf_conntrack_lock); + if (err < 0 && master_ct) nf_ct_put(master_ct);