5.15-stable review patch. If anyone has any objections, please let me know.
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From: Danielle Costantino dcostantino@meta.com
[ Upstream commit d2099d9f16dbfa1c5266d4230ff7860047bb0b68 ]
The rate limiting validation condition currently checks the output variable max_bw_value[i] instead of the input value maxrate->tc_maxrate[i]. This causes the validation to compare an uninitialized or stale value rather than the actual requested rate.
The condition should check the input rate to properly validate against the upper limit:
} else if (maxrate->tc_maxrate[i] <= upper_limit_gbps) {
This aligns with the pattern used in the first branch, which correctly checks maxrate->tc_maxrate[i] against upper_limit_mbps.
The current implementation can lead to unreliable validation behavior:
- For rates between 25.5 Gbps and 255 Gbps, if max_bw_value[i] is 0 from initialization, the GBPS path may be taken regardless of whether the actual rate is within bounds
- When processing multiple TCs (i > 0), max_bw_value[i] contains the value computed for the previous TC, affecting the validation logic
- The overflow check for rates exceeding 255 Gbps may not trigger consistently depending on previous array values
This patch ensures the validation correctly examines the requested rate value for proper bounds checking.
Fixes: 43b27d1bd88a ("net/mlx5e: Fix wraparound in rate limiting for values above 255 Gbps") Signed-off-by: Danielle Costantino dcostantino@meta.com Reviewed-by: Gal Pressman gal@nvidia.com Link: https://patch.msgid.link/20251124180043.2314428-1-dcostantino@meta.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/mellanox/mlx5/core/en_dcbnl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_dcbnl.c b/drivers/net/ethernet/mellanox/mlx5/core/en_dcbnl.c index 86545554abb4e..dae944d28ee26 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_dcbnl.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_dcbnl.c @@ -606,7 +606,7 @@ static int mlx5e_dcbnl_ieee_setmaxrate(struct net_device *netdev, MLX5E_100MB); max_bw_value[i] = max_bw_value[i] ? max_bw_value[i] : 1; max_bw_unit[i] = MLX5_100_MBPS_UNIT; - } else if (max_bw_value[i] <= upper_limit_gbps) { + } else if (maxrate->tc_maxrate[i] <= upper_limit_gbps) { max_bw_value[i] = div_u64(maxrate->tc_maxrate[i], MLX5E_1GB); max_bw_unit[i] = MLX5_GBPS_UNIT;