[PATCH] net/mlx5e: TC, fix internal port leak when a flow is reoffloaded

[PATCH] net/mlx5e: TC, fix internal port leak when a flow is reoffloaded

[Wentao Liang]

For a flow originating from an OVS internal port,
mlx5e_tc_add_fdb_flow() takes a reference on the internal port and stores
it in the flow's esw attribute.

If the flow cannot be offloaded because the encap route is not available
(-ENETUNREACH) on a multipath LAG setup, __mlx5e_add_fdb_flow() keeps the
flow on the unready list instead of freeing it. When
mlx5e_tc_reoffload_flows_work() retries, mlx5e_tc_add_fdb_flow() takes
another reference and overwrites the stored pointer, so the previous
reference is never dropped.

Only look up the internal port if the flow does not hold a reference
already; the reference is released together with the flow attributes.

Fixes: 166f431ec6be ("net/mlx5e: Add indirect tc offload of ovs internal port")
Cc: stable@vger.kernel.org
Assisted-by: DeepSeek-V4.1-Flash and OpenAI Codex
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
 .../net/ethernet/mellanox/mlx5/core/en_tc.c   | 22 ++++++++++---------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
index 17bd92529a44..8246378b089f 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -2005,17 +2005,19 @@ mlx5e_tc_add_fdb_flow(struct mlx5e_priv *priv,
 			goto err_out;
 		}
 
-		int_port = mlx5e_tc_int_port_get(mlx5e_get_int_port_priv(priv),
-						 parse_attr->filter_dev->ifindex,
-						 flow_flag_test(flow, EGRESS) ?
-						 MLX5E_TC_INT_PORT_EGRESS :
-						 MLX5E_TC_INT_PORT_INGRESS);
-		if (IS_ERR(int_port)) {
-			err = PTR_ERR(int_port);
-			goto err_out;
-		}
+		if (!esw_attr->int_port) {
+			int_port = mlx5e_tc_int_port_get(mlx5e_get_int_port_priv(priv),
+							 parse_attr->filter_dev->ifindex,
+							 flow_flag_test(flow, EGRESS) ?
+							 MLX5E_TC_INT_PORT_EGRESS :
+							 MLX5E_TC_INT_PORT_INGRESS);
+			if (IS_ERR(int_port)) {
+				err = PTR_ERR(int_port);
+				goto err_out;
+			}
 
-		esw_attr->int_port = int_port;
+			esw_attr->int_port = int_port;
+		}
 	}
 
 	err = post_process_attr(flow, attr, extack);
-- 
2.34.1

Re: [PATCH] net/mlx5e: TC, fix internal port leak when a flow is reoffloaded

[netdev-bot+sinfo]

Hi!

This is an automated message. This series looks like a fix, but its
commit messages seem to be missing some information:

 - How the issue was discovered, e.g. hit in production, hit during
   development, syzbot report, manual code inspection, LLM or static
   analysis tool scan.

 - Whether the issue was actually triggered, or is only theoretical
   (e.g. found by code inspection). If it was triggered please include
   the symptoms, like the stack trace or error messages.

 - What hardware the change was tested on. For driver fixes please
   mention the device (and if relevant firmware version) used for
   testing, or say that the change was not tested on real hardware.

Please do not repost the series just to address the above. Instead,
reply to this email with the missing information, so that reviewers
can take it into account. If the series needs another revision for
other reasons, please include the information in the commit messages
then.

The evaluation is done by an LLM so it may be wrong, if you think
that is the case please reply and explain.