Module cwe_checker_lib::analysis::stack_alignment_substitution

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Expand description

Substitutes stack pointer alignment operations utilising logical AND with an arithmetic SUB operation.

The first basic block of every function is searched for a logical AND operation on the stack pointer. By journaling changes to the stack pointer an offset is calculated which is going to be used to alter the operation into a subtraction.

Log Messages

Following cases trigger log messages:

  • alignment is untypical for the architecture
  • the argument for the AND operation is not a constant
  • an operation alters the stack pointer, which can not be journaled.

Functions

  • substitute_and_on_stackpointer
    Substitutes logical AND on the stackpointer register by SUB. Expressions are changed to use constants w.r.t the provided bit mask.