Tag-Protector: An Effective and Dynamic Detection of Illegal Memory Accesses through Compile Time Code Instrumentation

Algorithm 5

Stage 5: tag checks placement.

Input: Instrumented LLVM-IR code generated in stage-4 of tag-protection pass; memory

   map table ; Dedicated tag address

Output: Final Instrumented LLVM-IR code generated through LLVM opt command using stage-5 of tag-protection pass

for each function definition in do

  for each instruction in do

    if is function call without definition and not a memory allocation or deallocation call then

     for each function argument in do

       Create two memory objects and . Retrieve respective

        and marks from .

       Read address location next to   address before instruction and

       store the read value in .

       Read address location next to address after instruction and store

       the read value in .

       Place tag check instruction after function call comparing and memory objects.

     end

    end

    if is a STORE instruction and updates a memory object then

     Retrieve respective and marks from and get address

     to be accessed by the instruction.

     Perform dangling pointer dereference check. compare with the .

     Perform address comparison checks: with the and .

    end

    if is a LOAD instruction and read from allocated memory object then

     Retrieve respective and marks from and get address to be accessed

     by the instruction.

     Perform dangling pointer dereference check. compare with the .

     Perform address comparison checks: with the and .

    end

  end

end

Delete memory map table .

Save modified LLVM-IR code as a final instrumented LLVM-IR code