net/mlx5e: Fix NULL pointer dereference in ioctl module EEPROM query

The mlx5_query_mcia() function unconditionally dereferences the status
pointer to store the MCIA register status value.
However, mlx5e_get_module_id() passes NULL since it doesn't need the
status value.

Add a NULL check before dereferencing the status pointer to prevent a
NULL pointer dereference.

Fixes: 2e4c44b ("net/mlx5: Refactor EEPROM query error handling to return status separately")
Signed-off-by: Gal Pressman <[email protected]>
Reviewed-by: Tariq Toukan <[email protected]>
Reviewed-by: Dragos Tatulea <[email protected]>
Signed-off-by: Mark Bloch <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: gal-pressman

drivers/net/ethernet/mellanox/mlx5/core/port.c

@@ -393,9 +393,11 @@ static int mlx5_query_mcia(struct mlx5_core_dev *dev,
 	if (err)
 		return err;
 
-	*status = MLX5_GET(mcia_reg, out, status);
-	if (*status)
+	if (MLX5_GET(mcia_reg, out, status)) {
+		if (status)
+			*status = MLX5_GET(mcia_reg, out, status);
 		return -EIO;
+	}
 
 	ptr = MLX5_ADDR_OF(mcia_reg, out, dword_0);
 	memcpy(data, ptr, size);