[PATCH net 3/4] net/mlx5e: Bounds-check stats_nch in mlx5e_get_queue_stats_rx()

[Tariq Toukan <tariqt@nvidia.com>]

From: Feng Liu <feliu@nvidia.com>

mlx5e_get_queue_stats_rx() is invoked by the netdev stats core with
an RX queue index 'i' from real_num_rx_queues. Today it only guards
against priv->stats_nch == 0 and then dereferences
priv->channel_stats[i] unconditionally.

During interface bring-up channel_stats[] is populated incrementally
by mlx5e_channel_stats_alloc(), so a concurrent QSTATS netlink dump
can call into the helper with i >= stats_nch. The non-zero check
passes, channel_stats[i] is NULL, and the dereference panics.

Replace the non-zero check with an upper-bound check against
stats_nch, which subsumes the zero check and prevents the
out-of-bounds dereference.

Fixes: 7b66ae536a78 ("net/mlx5e: Add per queue netdev-genl stats")
Signed-off-by: Feng Liu <feliu@nvidia.com>
Reviewed-by: Eran Ben Elisha <eranbe@nvidia.com>
Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
Reviewed-by: Nimrod Oren <noren@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 8f2b3abe0092..42a658402592 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -5489,7 +5489,7 @@ static void mlx5e_get_queue_stats_rx(struct net_device *dev, int i,
 	struct mlx5e_rq_stats *xskrq_stats;
 	struct mlx5e_rq_stats *rq_stats;
 
-	if (mlx5e_is_uplink_rep(priv) || !priv->stats_nch)
+	if (mlx5e_is_uplink_rep(priv) || i >= priv->stats_nch)
 		return;
 
 	channel_stats = priv->channel_stats[i];
-- 
2.44.0