Dendritic growth of lithium (Li) metal is a leading cause of degradation and catastrophic failure of all-solid-state batteries (ASSBs) with Li anode. Insertion of a buffer layer between the Li metal and the solid electrolyte is known to ameliorate this phenomenon, yet the identification of an optimal buffer material, and the design of ASSBs that can be manufactured at scale, remains elusive and largely driven by trial-and-error experimentation. Our analysis seeks to accelerate the buffer-materials discovery by elucidating the conditions under which the buffer's presence stabilizes electrodeposition on the Li anode in ASSBs. The analysis quantifies the interfacial instability associated with dendrite formation in terms of the battery's operating conditions and the electrochemical and physical properties of the buffer material and solid electrolyte. The model predicts that, among several prospective buffer materials, Ag, Al, Sn, and antiperovskite super ionic conductor, Li3S(BF4)0.5Cl0.5, are effective in stabilizing electrodeposition and suppressing dendrite growth. Our model's predictions of the dendrite suppression abilities of different buffer materials are consistent with the published experimental findings. The model can be used to guide experimental and computational discovery of new buffer materials that match a particular electrolyte.