Re: [PATCH net v3 1/2] net/mlx5: HWS, fix modify header pattern compare on big-endian

[Yevgeny Kliteynik <kliteyn@nvidia.com>]

On 19-Oct-26 16:31, Alexandre Cassen wrote:
> mlx5hws_pat_compare_pattern() casts each __be64 action to __be32 to
> compare only its control dword. On big-endian this keeps the data dword
> instead, which HWS clears from the pattern of set and add actions. Two
> such actions writing the same value into different fields then share a
> pattern and the second rule modifies the wrong field.
> 
> Read the first dword of each action from memory instead. Little-endian
> behavior is unchanged.
> 
> Discovered by an AI code review agent [1] and confirmed by code
> inspection. Not reproduced for lack of big-endian hardware running HWS.
> Tested for regressions on ConnectX-7 with firmware 28.48.1000 on a
> little-endian host.
> 
> Fixes: aefc15a0fa1c ("net/mlx5: HWS, added modify header pattern and args handling")
> Link: https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20261010120147.135825-1-acassen%40corp.free.fr [1]
> Reviewed-by: Simon Horman <horms@kernel.org>
> Reviewed-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
> Signed-off-by: Alexandre Cassen <acassen@corp.free.fr>
> ---
>   .../net/ethernet/mellanox/mlx5/core/steering/hws/pat_arg.c    | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> 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..512299b59fd0 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
> @@ -116,8 +116,8 @@ static bool mlx5hws_pat_compare_pattern(int cur_num_of_actions,
>   				return false;
>   		} else {
>   			/* Compare just the control, not the values */
> -			if ((__force __be32)actions[i] !=
> -			    (__force __be32)cur_actions[i])
> +			if (*(__be32 *)&actions[i] !=
> +			    *(__be32 *)&cur_actions[i])
>   				return false;
>   		}
>   	}

Reviewed-by: Yevgeny Kliteynik <kliteyn@nvidia.com>