This study addresses the origin of the substance filling coronal mass ejections (CMEs). We investigated the 19 Oct 2011 major solar flare accompanied by a «halo»-type high-velocity CME that caused a powerful magnetospheric storm on the Earth two days after. We made the estimates for the substance flows that permeated into the corona through the areas of two dimmings located on the flare's either side. The total (3–7)·1014 g substance is shown to have risen to the coronal ejection eruptive structures from its chromospheric bases within the flare onset and its soft X-ray maximum (~103 s). When accounting for the filament substance ejected with the CME and dynamic peculiarities of the plasma density distribution in the bases, the total estimate reaches the representative value (~1015 g) for large coronal mass ejections from the LASCO/SOHO catalogue.