def allocate_stack(size=DEFAULT_STACK_SIZE):
"""Allocate some memory that can be used as a stack.
@return: a ctypes void pointer to the *top* of the stack.
"""
# Allocate memory with appropriate flags for a stack as in https://blog.fefe.de/?ts=a85c8ba7
base = libc.mmap(
None, size + GUARD_PAGE_SIZE, libc.PROT_READ | libc.PROT_WRITE,
libc.MAP_PRIVATE | libc.MAP_ANONYMOUS | libc.MAP_GROWSDOWN |
libc.MAP_STACK, -1, 0)
try:
# create a guard page that crashes the application when it is written to (on stack overflow)
libc.mprotect(base, GUARD_PAGE_SIZE, libc.PROT_NONE)
yield ctypes.c_void_p(base + size + GUARD_PAGE_SIZE)
finally:
libc.munmap(base, size + GUARD_PAGE_SIZE)
def allocate_stack(size=DEFAULT_STACK_SIZE):
"""Allocate some memory that can be used as a stack.
@return: a ctypes void pointer to the *top* of the stack.
"""
# Allocate memory with appropriate flags for a stack as in https://blog.fefe.de/?ts=a85c8ba7
base = libc.mmap(
None,
size + GUARD_PAGE_SIZE,
libc.PROT_READ | libc.PROT_WRITE,
libc.MAP_PRIVATE | libc.MAP_ANONYMOUS | libc.MAP_GROWSDOWN | libc.MAP_STACK,
-1, 0)
try:
# create a guard page that crashes the application when it is written to (on stack overflow)
libc.mprotect(base, GUARD_PAGE_SIZE, libc.PROT_NONE)
yield ctypes.c_void_p(base + size + GUARD_PAGE_SIZE)
finally:
libc.munmap(base, size + GUARD_PAGE_SIZE)