[PATCH 5/6] netfilter: flowtable: set NF_FLOW_TEARDOWN flag on entry expiration

[Pablo Neira Ayuso]

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 <pa...@mellanox.com>
Reviewed-by: Roi Dayan <r...@mellanox.com>
Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.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 4344e572b7f9..42da6e337276 100644
--- a/net/netfilter/nf_flow_table_core.c
+++ b/net/netfilter/nf_flow_table_core.c
@@ -284,7 +284,7 @@ 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);
@@ -361,8 +361,10 @@ 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