With refcount_inc_not_zero, we'd also need a smp_rmb or similar,
followed by a test of the CONFIRMED bit.
However, the ct pointer is taken from skb->_nfct, its refcount must
not be 0 (else, we'd already have a use-after-free bug).
Use refcount_inc() instead to clarify the ct refcount is expected to
be at least 1.
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
---
A followp to 'netfilter: conntrack: fix crash due to confirmed bit load reordering',
but target next as current code works fine.
diff --git a/net/netfilter/nf_flow_table_core.c b/net/netfilter/nf_flow_table_core.c
index f2def06d1070..cca2358c10a1 100644
--- a/net/netfilter/nf_flow_table_core.c
+++ b/net/netfilter/nf_flow_table_core.c
@@ -53,14 +53,14 @@ struct flow_offload *flow_offload_alloc(struct nf_conn *ct)
{
struct flow_offload *flow;
- if (unlikely(nf_ct_is_dying(ct) ||
- !refcount_inc_not_zero(&ct->ct_general.use)))
+ if (unlikely(nf_ct_is_dying(ct)))
return NULL;
flow = kzalloc(sizeof(*flow), GFP_ATOMIC);
if (!flow)
- goto err_ct_refcnt;
+ return NULL;
+ refcount_inc(&ct->ct_general.use);
flow->ct = ct;
flow_offload_fill_dir(flow, FLOW_OFFLOAD_DIR_ORIGINAL);
@@ -72,11 +72,6 @@ struct flow_offload *flow_offload_alloc(struct nf_conn *ct)
__set_bit(NF_FLOW_DNAT, &flow->flags);
return flow;
-
-err_ct_refcnt:
- nf_ct_put(ct);
-
- return NULL;
}
EXPORT_SYMBOL_GPL(flow_offload_alloc);
--
2.35.1
