[EPIC] santize user input in ExecCmd function

[neo-liang-sap]

see discussion in #267 (comment)

I will use this issue to track all ExecCmd refactor work, and will list files i refactored here (to be appended as i'm continue working)

the ExecCmd function should not be called with a cmd string and instead the caller should pass the name and arguments directly for exec.Command, otherwise an attacker could sneak in arguments

[neo-liang-sap]

• drop.go - santize user input in ExeCmdXXX for drop.go #324

[neo-liang-sap]

close this issue as @tedteng has built many sub issue to track this
i will track my work and effort in different PR (each PR for one refactor)
/close