Implementation of Soft Protections to Safeguard Program Execution

• US 20080016305A1
• Filed: 07/12/2006
• Published: 01/17/2008
• Est. Priority Date: 07/12/2006
• Status: Abandoned Application

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Heffley, Daniel A., Chen, Chiahong, Lewis, Russell L.
• Application Number:
  US11/457,093
• Publication Number:
  US 20080016305A1
• Time in Patent Office: Days
• US Class Current: 711/163
• CPC Class Codes: G06F 12/145 the protection being virtual, e.g. for virtual blocks or segments before a translation mechanism

Abstract

A program executing on a computer system implements a soft protection by allocating a region of memory in the computer system, initializing a soft protection on a page in the region of memory, detecting a use of the page having the soft protection, receiving a signal from an operating system executing on the computer system, and determining if the signal is masked off. An operating system module executes on a computer system for implementing a soft protection. The operating system module includes an initialization module for allocating memory, a settings module for saving a previous soft protection setting, a detection module for detecting a page fault, and an execution module for setting a notification signal, clearing the soft protection and restoring page permissions.

Claims

1. A method of implementing a soft protection by a program executing on a computer system, comprising:

allocating a region of memory in the computer system;

initializing a soft protection on a page in the region of memory;

detecting a use of the page having the soft protection;

receiving a first signal from an operating system executing on the computer system; and

determining if the signal is masked off, wherein if the signal is not masked off a signal handler in the program executes.

2. The method of claim 1, wherein detecting the use of the page having the soft protection is performed by an operating system executing on the computer system.

3. The method of claim 2, further including queuing a second signal for the program by the operating system.

4. The method of claim 3, further including disabling the soft protection by the operating system to give the program access to the page.

5. The method of claim 4, further including returning control to the program by the operating system.

6. The method of claim 1, further including performing reporting or handling.

7. The method of claim 6, further including returning from the signal handler once the reporting or handling is completed.

8. An operating system module executing on a computer system for implementing a soft protection, comprising:

an initialization module which initializes a memory allocation in the computer system without the soft protection;

a settings module following the initialization module which saves a previous protection setting and initializes an effective setting to match a current setting of the soft protection;

a detection module following the settings module which identifies whether the soft protection was enabled; and

an execution module following the detection module which sets a signal, clears the soft protection, and restores page permissions.

9. The module of claim 8, further including a handling module following the settings module for performing page fault handling.

10. The module of claim 9, further including a return module following the handling module for returning control of the computer system to a user, wherein the return module delivers a signal to a program executing on the computer system.

11. The module of claim 10, wherein if the return module determines the signal to be masked off;

the signal is queued for later delivery.

12. The module of claim 8, wherein the detection module is operable to determine whether a hard protection and the soft protection coincide in a single memory allocation.

13. The module of claim 12, wherein the settings module is operable to merge the hard and soft protections.

14. A method of implementing a stack overflow notification for a program, comprising:

determining if a page fault has occurred;

determining if a predefined stack warning value has been set for a thread in the program;

determining if a stack extension invades a predefined stack warning area; and

receiving a stack warning signal to the thread.

15. The method of claim 14, further including determining if the stack warning signal is masked off.

16. The method of claim 15, further including performing signal handling.

17. The method of claim 16, wherein the signal handling is immediately performed upon a determination that the stack warning signal is not masked off.

18. The method of claim 15, wherein the signal is queued upon a determination that the stack warning signal is masked off.

19. The method of claim 14, wherein the stack warning signal is sent to the thread via an operating system kernel.