Safer mechanism for using pointers to code

• US 9,026,859 B1
• Filed: 03/14/2012
• Issued: 05/05/2015
• Est. Priority Date: 03/14/2012
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Pike, Geoffrey Roeder
• Primary Examiner(s): Manoskey, Joseph D
• Application Number:
  US13/419,997
• Time in Patent Office: 1,147 Days
• Field of Search: 714/6.1, 714/21, 714/25, 714/38.1, 714/38.13, 714/42, 714/47.1, 714/53
• US Class Current: 714/42
• CPC Class Codes: G06F 11/00 Error detection; Error correction; Monitoring error detection, correction or monitoring in information storage based on relative movement between record carrier and transducer G11B20/18; monitoring, i.e. supervising the progress of recording or reproducing G11B27/36; in static stores G11C29/00
• CPC Class Codes: G06F 11/073 in a memory management context, e.g. virtual memory or cache management memory management G06F12/00; testing of static memory units G11C29/00
• CPC Class Codes: G06F 11/0793 Remedial or corrective actions recovery from an exception in an instruction pipeline G06F9/3861; by retry G06F11/1402; for recovering from a failure of a protocol instance or entity H04L69/40
• CPC Class Codes: G06F 11/3037 where the computing system component is a memory, e.g. virtual memory, cache accessing, addressing or allocating within memory systems or architectures G06F12/00; checking stores for correct operation G11C29/00
• CPC Class Codes: G06F 21/79 in semiconductor storage media, e.g. directly-addressable memories

Abstract

Systems, methods, and computer storage mediums are provided for mitigating damage to data caused by a computer process having a corrupted pointer. An exemplary method includes receiving a pointer to a memory address. The pointer is received in conjunction with a command of the computer process to access data stored at the memory address, where the data is intended to be stored in a memory segment that allows for read-only access. The memory segment that includes the memory address is analyzed to determine a modification state for the memory segment, where the modification state indicates the type of access that the memory segment allows. The computer process is halted when the modification state indicates that the memory segment allows for other than read-only access.

Claims

1. A computer-implemented method for mitigating damage to data caused by a computer process having a corrupted pointer, the method comprising:

receiving, by at least one computer processor, a pointer to a memory address, the pointer received in conjunction with a command by the computer process to access data stored at the memory address, wherein the data is intended to be stored in a memory segment that allows for read-only access, wherein the data comprises a function pointer to an executable code function;

analyzing, by at least one computer processor, the memory segment that includes the memory address to determine a modification state for the memory segment, wherein the modification state indicates the type of access that the memory segment allows; and

halting, by at least one processor, the computer process when the modification state indicates that the memory segment allows for other than read-only access.

2. The computer-implemented method of claim 1, wherein the function pointer is included in a virtual function table.

3. The computer-implemented method of claim 1, further comprising:

generating a fault code indicating that the computer process is halted due to the memory address being in a memory segment that allows for writable access.

4. The computer-implemented method of claim 1, wherein data at the memory address includes inputs to a computation that, when provided to the computer processor, determine the location of additional data.

5. The computer-implemented method of claim 1, wherein data at the memory address includes a name of a function that includes executable instructions.

6. The computer-implemented method of claim 1, wherein data at the memory address includes a name of a file that includes executable instructions.

7. A system for mitigating damage to data caused by a computer process having a corrupted pointer, the system comprising:

a memory; and

a computer processor coupled to the memory and configured to;

receive a pointer to a memory address of the memory, the pointer received in conjunction with a command by the computer process to access data stored at the memory address, wherein the data is intended to be stored in a memory segment that allows for read-only access, wherein the data comprises a function pointer to an executable code function;

analyze the memory segment that includes the memory address to determine a modification state for the memory segment, wherein the modification state indicates the type of access that the memory segment allows; and

halt the computer process when the modification state indicates that the memory segment allows for other than read-only access.

8. The system of claim 7, wherein the function pointer is included in a virtual function table.

9. The system of claim 7, wherein the computer processor is further configured to generate a fault code indicating that the computer process is halted due to the memory address being in a memory segment that allows for writable access.

10. The system of claim 7, wherein data at the memory address includes inputs to a computation that, when provided to the computer processor, determine the location of additional data.

11. The system of claim 7, wherein data at the memory address includes a name of a function that includes executable instructions.

12. The system of claim 7, wherein data at the memory address includes a name of a file that includes executable instructions.

13. A computer readable storage medium having instructions encoded thereon that, when executed by a computing device, causes the computing device to perform operations comprising:

receiving a pointer to a memory address, the pointer received in conjunction with a command by the computer process to access data stored at the memory address, wherein the data is intended to be stored in a memory segment that allows for read-only access, wherein the data comprises a function pointer to an executable code function;

analyzing the memory segment that includes the memory address to determine a modification state for the memory segment, wherein the modification state indicates the type of access that the memory segment allows; and

halting the computer process when the modification state indicates that the memory segment allows for other than read-only access.

14. The computer readable storage medium of claim 13, wherein the function pointer is included in an object'"'"'s virtual function table.

15. The computer readable storage medium of claim 13, further comprising:

generating a fault code indicating that the computer process is halted due to the memory address being in a memory segment that allows for writable access.

16. The computer readable storage medium of claim 13, wherein data at the memory address includes inputs to a computation that, when provided to the computer processor, determine the location of additional data.

17. The computer readable storage medium of claim 13, wherein the memory address includes a name of a function that includes executable instructions.

18. The computer readable storage medium of claim 13, wherein the memory address includes a name of a file that includes executable instructions.

19. A computer-implemented method for compiling a computer programming language in order to mitigate damage to data caused by a resulting computer program that, when executed, has a corrupted pointer that references executable instructions, the method comprising:

analyzing, by at least one computer processor, a block of code to determine a jump instruction to the executable instructions;

inserting, before the jump instruction, by at least one computer processor, one or more verification instructions that, when executed, verify that a pointer to the executable instructions referenced by the jump instruction reside in a read-only memory location;

inserting, before the jump, by at least one computer processor, one or more halt instructions that, when executed, halt the computer program when the pointer to the executable instructions referenced by the jump instruction reside in a writable memory location.