The UniswapAnchoredView returns price for Zero address (0x00).

[akshaysrivastav]

Issue

The current oracle implementation that the Compound Protocol uses which is deployed at 0x4007B71e01424b2314c020fB0344b03A7C499E1A returns a price value from getUnderlyingPrice() function when the zero address (0x00) is passed.

This issue however does not break any compound protocol functionality but still getting a price value for an invalid input is not ideal.

Cause

The reason for this issue seems to be due to the addition of TokenConfig for LINK, KNC and SNX tokens. These three configs were added without a cToken address value.

Resolution

The getUnderlyingPrice() function should check the validity of the input address variable (input should not be equal to 0x00).