'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@xxxxxxxxx>
---
With this patch I do not see any more stale entries on the dying list with eache evictor
not being scheduled. Such 'leaked' entries are easy to spot since their 'use' count
is growing, i.e. invoking conntrack -L dying repeatedly yields 'use=$bignum++' output.
net/netfilter/nf_conntrack_netlink.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 5857963..7e89c1a 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -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);
@@ -1166,6 +1166,8 @@ ctnetlink_dump_list(struct sk_buff *skb, struct netlink_callback *cb, bool dying
if (cb->args[0] == nr_cpu_ids)
return 0;
+ last = (struct nf_conn *)cb->args[1];
+
for (cpu = cb->args[0]; cpu < nr_cpu_ids; cpu++) {
struct ct_pcpu *pcpu;
@@ -1174,7 +1176,6 @@ 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) {
@@ -1193,7 +1194,8 @@ 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[1] = (unsigned long)ct;
spin_unlock_bh(&pcpu->lock);
goto out;
--
1.8.1.5
--
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