The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 25, 2009
Filed:
Apr. 18, 2007
Andrew H. White, Baltimore, MD (US);
Andrew H. White, Baltimore, MD (US);
Abstract
A method of protecting a return address on a computer stack is disclosed. Two stacks are created, the first a normal stack, and the second, or shadow, having shadow frames containing the return address upon a subroutine call, the address on the first stack where the return address is stored, and a user-definable state variable which is used to identify a shadow frame as a return address. Before returning from a subroutine, the two return addresses are compared, and if they do not match, the second stack is searched down, and then up, for a matching return address. If there is a match, the shadow is re-synchronized with the first stack by comparing the stored values of the first stack pointer with the first stack pointer and adjusting appropriately the shadow stack pointer. The matching shadow frame must also be a return address datatype of return address.