[PATCH 5.6 109/194] netfilter: flowtable: set NF_FLOW_TEARDOWN flag on entry expiration

Greg Kroah-Hartman
2020-05-18T18:11:49Z

From: Pablo Neira Ayuso <pablo@netfilter.org>

[ Upstream commit 9ed81c8e0deb7bd2aa0d69371e4a0f9a7b31205d ]

If the flow timer expires, the gc sets on the NF_FLOW_TEARDOWN flag.
Otherwise, the flowtable software path might race to refresh the
timeout, leaving the state machine in inconsistent state.

Fixes: c29f74e0df7a ("netfilter: nf_flow_table: hardware offload support")
Reported-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/netfilter/nf_flow_table_core.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/net/netfilter/nf_flow_table_core.c b/net/netfilter/nf_flow_table_core.c
index 70ebebaf5bc12..0ee78a1663786 100644
--- a/net/netfilter/nf_flow_table_core.c
+++ b/net/netfilter/nf_flow_table_core.c
@@ -271,7 +271,7 @@ static void flow_offload_del(struct nf_flowtable *flow_table,

if (nf_flow_has_expired(flow))
flow_offload_fixup_ct(flow->ct);
- else if (test_bit(NF_FLOW_TEARDOWN, &flow->flags))
+ else
flow_offload_fixup_ct_timeout(flow->ct);

flow_offload_free(flow);
@@ -348,8 +348,10 @@ static void nf_flow_offload_gc_step(struct flow_offload *flow, void *data)
{
struct nf_flowtable *flow_table = data;

- if (nf_flow_has_expired(flow) || nf_ct_is_dying(flow->ct) ||
- test_bit(NF_FLOW_TEARDOWN, &flow->flags)) {
+ if (nf_flow_has_expired(flow) || nf_ct_is_dying(flow->ct))
+ set_bit(NF_FLOW_TEARDOWN, &flow->flags);
+
+ if (test_bit(NF_FLOW_TEARDOWN, &flow->flags)) {
if (test_bit(NF_FLOW_HW, &flow->flags)) {
if (!test_bit(NF_FLOW_HW_DYING, &flow->flags))
nf_flow_offload_del(flow_table, flow);
--
2.20.1