It gets very interesting if there actually are no stocks to buy back in the market. For details on how it gets interesting google "short squeeze".

Other than that exceptional situation it's not that asymmetrical:

-Typically you have to post some collateral for shorting and there will be a well-understood maximum loss before your broker buys back the stock and seizes your collateral to cover that loss. So short (haha) of a short squeeze there actually is a maximum loss in short selling.

-You can take similar risks on the long side by buying stocks on credit ("on margin" in financial slang) with collateral, which the bank will use to close your position if the stock drops too far. So basically long risks also can be made as big as your borrowing ability.