Dynamic call tracking method based on CPU interrupt instructions to improve disassembly quality of indirect calls

Patent metadata

Field	Value
Publication number	US-9767004-B2
Application number	US-201414305580-A
Country	US
Kind code	B2
Filing date	Jun 16, 2014
Priority date	Jun 16, 2014
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

Embodiments presented herein describe techniques to track and correct indirect function calls in disassembled object code. Assembly language source code is generated from a binary executable object. The assembly language source code may include indirect function calls. Memory addresses associated with the function calls are identified. A central processing unit (CPU) interrupt instruction is inserted in the disassembled source code at each indirect function call. The disassembled source code is executed. When the interrupt at each indirect function call is triggered, the function name of a function referenced by a register may be determined.

First claim

What is claimed is:

1. A method for disassembling compiled object code, the method comprising:
disassembling a binary executable object to generate assembly language source code, wherein the assembly language source code includes one or more indirect function calls and wherein each indirect function call corresponds to a function dynamically identified using an address identified when executing the assembly language source code;
converting one or more of the indirect function calls to one or more central processing unit (CPU) interrupt instructions;
executing the assembly language source code;
upon reaching the interrupt instruction to which each indirect function call was converted while executing the assembly language source code, determining a register value stored in a register specified in the indirect function call, wherein the register value specifies a memory address of the identified function; and
for each interrupt instruction, replacing, in the assembly language source code, the register specified in the indirect function call that was converted to the interrupt instruction with a function name corresponding to the register value, and invoking the identified function.

2. The method of claim 1 , wherein the interrupt instruction transfers control of the execution to a debugger module executed to determine the function name.

3. The method of claim 1 , wherein the register value specifies a memory address stored in the register when the interrupt instruction is triggered.

4. The method of claim 1 , wherein the function name is identified from a memory address stored in the register when the interrupt instruction is triggered.

5. The method of claim 1 , wherein the assembly language source code is generated by a disassembler.

6. The method of claim 1 , wherein the interrupt instruction is INT 3 .

7. The method of claim 1 , wherein the assembly language source code is executed in a debugger module.

8. A non-transitory computer-readable storage medium storing instructions, which, when executed on a processor, performs an operation for disassembling compiled object code, the operation comprising:
disassembling a binary executable object to generate assembly language source code, wherein the assembly language source code includes one or more indirect function calls and wherein each indirect function call corresponds to a function dynamically identified using an address identified when executing the assembly language source code;
converting one or more of the indirect function calls to one or more central processing unit (CPU) interrupt instructions;
executing the assembly language source code;
upon reaching the interrupt instruction to which each indirect function call was converted while executing the assembly language source code, determining a register value stored in a register specified in the indirect function call, wherein the register value specifies a memory address of the identified function; and
for each interrupt instruction, replacing, in the assembly language source code, the register specified in the indirect function call that was converted to the interrupt instruction with a function name corresponding to the register value, and invoking the identified function.

9. The non-transitory computer-readable storage medium of claim 8 , wherein the interrupt instruction transfers control of the execution to a debugger module executed to determine the function name.

10. The non-transitory computer-readable storage medium of claim 8 , wherein the register value specifies a memory address stored in the register when the interrupt instruction is triggered.

11. The non-transitory computer-readable storage medium of claim 8 , wherein the function name is identified from a memory address stored in the register when the interrupt instruction is triggered.

12. The non-transitory computer-readable storage medium of claim 8 , wherein the assembly language source code is generated by a disassembler.

13. The non-transitory computer-readable storage medium of claim 8 , wherein the interrupt instruction is INT 3 .

14. The non-transitory computer-readable storage medium of claim 8 , wherein the assembly language source code is executed in a debugger module.

15. A system, comprising:
a processor; and
a memory storing one or more application programs configured to perform an operation for disassembling compiled object code, the operation comprising:
disassembling a binary executable object to generate assembly language source code, wherein the assembly language source code includes one or more indirect function calls and wherein each indirect function call corresponds to a function dynamically identified using an address identified when executing the assembly language source code,
converting one or more of the indirect function calls to one or more central processing unit (CPU) interrupt instructions,
executing the assembly language source code,
upon reaching the interrupt instruction to which each indirect function call was converted while executing the assembly language source code, determining a register value stored in a register specified in the indirect function call, wherein the register value specifies a memory address of the identified function, and
for each interrupt instruction, replacing, in the assembly language source code, the register specified in the indirect function call that was converted to the interrupt instruction with a function name corresponding to the register value, and invoking the identified function.

16. The system of claim 15 , wherein the interrupt instruction transfers control of the execution to a debugger module executed to determine the function name.

17. The system of claim 15 , wherein the register value specifies a memory address stored in the register when the interrupt instruction is triggered.

18. The system of claim 15 , wherein the function name is identified from a memory address stored in the register when the interrupt instruction is triggered.

19. The system of claim 15 , wherein the assembly language source code is generated by a disassembler.

20. The system of claim 15 , wherein the interrupt instruction is INT 3 .

Assignees

• Symantec Corp

Inventors

• Yang hong yi
• Guo Rui

Classifications

• G06F11/3624 Primary

  by performing operations on the source code, e.g. via a compiler · CPC title

• G06F8/53

  Decompilation; Disassembly · CPC title