[PATCH net] net/mlx5: HWS, fix modify header pool match for copy actions

[Alexandre Cassen <acassen@corp.free.fr>]

mlx5_fs_hws_mh_pool_match() compares only the first half of each action
since rules pass their values as arguments. Copy and add_field actions
keep their destination in the second half and HWS reads them from the
pattern alone. Two modify headers whose copies differ only in
destination then share a pool and the second rule writes to the wrong
field.

Use the HWS core comparison that checks these actions in full.

Found while checking a Sashiko AI review report and confirmed against
the HWS pattern code. Not reproduced. No in-kernel user puts such
actions on the FDB but RDMA flow actions can.

Fixes: b36315ca69cb ("net/mlx5: fs, add HWS modify header API function")
Signed-off-by: Alexandre Cassen <acassen@corp.free.fr>
---
Sashiko AI review: https://sashiko.dev/#/patchset/20261008204230.3222198-1-acassen@corp.free.fr?part=2

 .../mlx5/core/steering/hws/fs_hws_pools.c         | 10 +++-------
 .../mellanox/mlx5/core/steering/hws/mlx5hws.h     | 15 +++++++++++++++
 .../mellanox/mlx5/core/steering/hws/pat_arg.c     |  8 ++++----
 3 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/fs_hws_pools.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/fs_hws_pools.c
index 86828e329187..cd888756e942 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/fs_hws_pools.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/fs_hws_pools.c
@@ -389,7 +389,7 @@ bool mlx5_fs_hws_mh_pool_match(struct mlx5_fs_pool *mh_pool,
 			       struct mlx5hws_action_mh_pattern *pattern)
 {
 	struct mlx5hws_action_mh_pattern *pool_pattern;
-	int num_actions, i;
+	int num_actions;
 
 	pool_pattern = mh_pool->pool_ctx;
 	if (WARN_ON_ONCE(!pool_pattern))
@@ -398,12 +398,8 @@ bool mlx5_fs_hws_mh_pool_match(struct mlx5_fs_pool *mh_pool,
 	if (pattern->sz != pool_pattern->sz)
 		return false;
 	num_actions = pattern->sz / MLX5_UN_SZ_BYTES(set_add_copy_action_in_auto);
-	for (i = 0; i < num_actions; i++) {
-		if ((__force __be32)pattern->data[i] !=
-		    (__force __be32)pool_pattern->data[i])
-			return false;
-	}
-	return true;
+	return mlx5hws_pat_compare_pattern(num_actions, pool_pattern->data,
+					   num_actions, pattern->data);
 }
 
 struct mlx5hws_action *mlx5_fc_get_hws_action(struct mlx5hws_context *ctx,
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/mlx5hws.h b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/mlx5hws.h
index 1ad7a50d938b..13e9cdbc5d47 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/mlx5hws.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/mlx5hws.h
@@ -688,6 +688,21 @@ mlx5hws_action_create_modify_header(struct mlx5hws_context *ctx,
 				    u32 log_bulk_size,
 				    u32 flags);
 
+/**
+ * mlx5hws_pat_compare_pattern - Compare two modify header patterns.
+ *
+ * @cur_num_of_actions: Number of actions in "cur_actions" array.
+ * @cur_actions: First pattern actions.
+ * @num_of_actions: Number of actions in "actions" array.
+ * @actions: Second pattern actions.
+ *
+ * Return: true if the patterns differ only in values, false otherwise.
+ */
+bool mlx5hws_pat_compare_pattern(int cur_num_of_actions,
+				 __be64 cur_actions[],
+				 int num_of_actions,
+				 __be64 actions[]);
+
 /**
  * mlx5hws_action_create_aso_meter - Create direct rule ASO flow meter action.
  *
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.c
index 9af449c2b4d5..0120d511c694 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.c
@@ -96,10 +96,10 @@ void mlx5hws_pat_uninit_pattern_cache(struct mlx5hws_pattern_cache *cache)
 	kfree(cache);
 }
 
-static bool mlx5hws_pat_compare_pattern(int cur_num_of_actions,
-					__be64 cur_actions[],
-					int num_of_actions,
-					__be64 actions[])
+bool mlx5hws_pat_compare_pattern(int cur_num_of_actions,
+				 __be64 cur_actions[],
+				 int num_of_actions,
+				 __be64 actions[])
 {
 	int i;
 
-- 
2.43.0