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netfilter: ctnetlink: fix refcnt leak in dying/unconfirmed list dumper

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'last' keeps track of the ct that had its refcnt bumped during previous
dump cycle.  Thus it must not be overwritten until end-of-function.

Another (unrelated, theoretical) issue: Don't attempt to bump refcnt of a conntrack
whose reference count is already 0.  Such conntrack is being destroyed
right now, its memory is freed once we release the percpu dying spinlock.

Fixes: b7779d06 ('netfilter: conntrack: spinlock per cpu to protect special lists.')
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2014-06-08 11:41:23 +02:00 committed by Pablo Neira Ayuso
parent 266155b2de
commit cd5f336f17
1 changed files with 5 additions and 3 deletions
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8
net/netfilter/nf_conntrack_netlink.c
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@ -1150,7 +1150,7 @@ static int ctnetlink_done_list(struct netlink_callback *cb)
static int
ctnetlink_dump_list(struct sk_buff *skb, struct netlink_callback *cb, bool dying)
{
struct nf_conn *ct, *last = NULL;
struct nf_conn *ct, *last;
struct nf_conntrack_tuple_hash *h;
struct hlist_nulls_node *n;
struct nfgenmsg *nfmsg = nlmsg_data(cb->nlh);
@ -1163,6 +1163,8 @@ ctnetlink_dump_list(struct sk_buff *skb, struct netlink_callback *cb, bool dying
if (cb->args[2])
return 0;
last = (struct nf_conn *)cb->args[1];
for (cpu = cb->args[0]; cpu < nr_cpu_ids; cpu++) {
struct ct_pcpu *pcpu;
@ -1171,7 +1173,6 @@ ctnetlink_dump_list(struct sk_buff *skb, struct netlink_callback *cb, bool dying
pcpu = per_cpu_ptr(net->ct.pcpu_lists, cpu);
spin_lock_bh(&pcpu->lock);
last = (struct nf_conn *)cb->args[1];
list = dying ? &pcpu->dying : &pcpu->unconfirmed;
restart:
hlist_nulls_for_each_entry(h, n, list, hnnode) {
@ -1190,7 +1191,8 @@ restart:
ct);
rcu_read_unlock();
if (res < 0) {
nf_conntrack_get(&ct->ct_general);
if (!atomic_inc_not_zero(&ct->ct_general.use))
continue;
cb->args[0] = cpu;
cb->args[1] = (unsigned long)ct;
spin_unlock_bh(&pcpu->lock);