116 lines
3.4 KiB
C
116 lines
3.4 KiB
C
/***
|
|
*resetstk.c - Recover from Stack overflow.
|
|
*
|
|
* Copyright (c) 1989-2001, Microsoft Corporation. All rights reserved.
|
|
*
|
|
*Purpose:
|
|
* Defines the _resetstkoflw() function.
|
|
*
|
|
*Revision History:
|
|
* 12-10-99 GB Module Created
|
|
* 04-17-01 PML Enable for Win9x, return success code (vs7#239962)
|
|
* 06-04-01 PML Do nothing if guard page not missing, don't shrink
|
|
* committed space (vs7#264306)
|
|
*
|
|
*******************************************************************************/
|
|
|
|
#include <stdlib.h>
|
|
#include <malloc.h>
|
|
#include <windows.h>
|
|
|
|
#define MIN_STACK_REQ_WIN9X 0x11000
|
|
#define MIN_STACK_REQ_WINNT 0x2000
|
|
|
|
/***
|
|
* void _resetstkoflw(void) - Recovers from Stack Overflow
|
|
*
|
|
* Purpose:
|
|
* Sets the guard page to its position before the stack overflow.
|
|
*
|
|
* Exit:
|
|
* Returns nonzero on success, zero on failure
|
|
*
|
|
*******************************************************************************/
|
|
|
|
int _resetstkoflw(void)
|
|
{
|
|
LPBYTE pStack, pGuard, pStackBase, pMaxGuard, pMinGuard;
|
|
MEMORY_BASIC_INFORMATION mbi;
|
|
SYSTEM_INFO si;
|
|
DWORD PageSize;
|
|
DWORD flNewProtect;
|
|
DWORD flOldProtect;
|
|
|
|
// Use _alloca() to get the current stack pointer
|
|
|
|
pStack = _alloca(1);
|
|
|
|
// Find the base of the stack.
|
|
|
|
if (VirtualQuery(pStack, &mbi, sizeof mbi) == 0)
|
|
return 0;
|
|
pStackBase = mbi.AllocationBase;
|
|
|
|
// Find the page just below where the stack pointer currently points.
|
|
// This is the highest potential guard page.
|
|
|
|
GetSystemInfo(&si);
|
|
PageSize = si.dwPageSize;
|
|
|
|
pMaxGuard = (LPBYTE) (((DWORD_PTR)pStack & ~(DWORD_PTR)(PageSize - 1))
|
|
- PageSize);
|
|
|
|
// If the potential guard page is too close to the start of the stack
|
|
// region, abandon the reset effort for lack of space. Win9x has a
|
|
// larger reserved stack requirement.
|
|
|
|
pMinGuard = pStackBase + ((_osplatform == VER_PLATFORM_WIN32_WINDOWS)
|
|
? MIN_STACK_REQ_WIN9X
|
|
: MIN_STACK_REQ_WINNT);
|
|
|
|
if (pMaxGuard < pMinGuard)
|
|
return 0;
|
|
|
|
// On a non-Win9x system, do nothing if a guard page is already present,
|
|
// else set up the guard page to the bottom of the committed range.
|
|
// For Win9x, just set guard page below the current stack page.
|
|
|
|
if (_osplatform != VER_PLATFORM_WIN32_WINDOWS) {
|
|
|
|
// Find first block of committed memory in the stack region
|
|
|
|
pGuard = pStackBase;
|
|
do {
|
|
if (VirtualQuery(pGuard, &mbi, sizeof mbi) == 0)
|
|
return 0;
|
|
pGuard = pGuard + mbi.RegionSize;
|
|
} while ((mbi.State & MEM_COMMIT) == 0);
|
|
pGuard = mbi.BaseAddress;
|
|
|
|
// If first committed block is already marked as a guard page,
|
|
// there is nothing that needs to be done, so return success.
|
|
|
|
if (mbi.Protect & PAGE_GUARD)
|
|
return 1;
|
|
|
|
// Fail if the first committed block is above the highest potential
|
|
// guard page. Should never happen.
|
|
|
|
if (pMaxGuard < pGuard)
|
|
return 0;
|
|
|
|
VirtualAlloc(pGuard, PageSize, MEM_COMMIT, PAGE_READWRITE);
|
|
}
|
|
else {
|
|
pGuard = pMaxGuard;
|
|
}
|
|
|
|
// Enable the new guard page.
|
|
|
|
flNewProtect = _osplatform == VER_PLATFORM_WIN32_WINDOWS
|
|
? PAGE_NOACCESS
|
|
: PAGE_READWRITE | PAGE_GUARD;
|
|
|
|
return VirtualProtect(pGuard, PageSize, flNewProtect, &flOldProtect);
|
|
}
|