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Finish the implementation of heap_debug_malloc_with_guard_page() using mprotect 

to make the guard page inaccessible. Thanks Ingo for the pointer!


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35488 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Michael Lotz 2010-02-15 23:48:51 +00:00
parent 22fb471ff0
commit 64bf879506
1 changed files with 14 additions and 4 deletions
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18
src/system/libroot/posix/malloc_debug/heap.cpp
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@ -10,10 +10,14 @@
*/
#include <malloc.h>
#include <malloc_debug.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/mman.h>
#include <locks.h>
#include <syscalls.h>
@ -1703,15 +1707,14 @@ heap_debug_dump_heaps(bool dumpAreas, bool dumpBins)
extern "C" void *
heap_debug_malloc_with_guard_page(size_t size)
{
size_t areaSize = ROUNDUP(size + sizeof(area_allocation_info), B_PAGE_SIZE);
size_t areaSize = ROUNDUP(size + sizeof(area_allocation_info) + B_PAGE_SIZE,
B_PAGE_SIZE);
if (areaSize < size) {
// the size overflowed
return NULL;
}
void *address = NULL;
// TODO: this needs a kernel backend (flag) to enforce adding an unmapped
// page past the required pages so it will reliably crash
area_id allocationArea = create_area("guarded area", &address,
B_ANY_ADDRESS, areaSize, B_NO_LOCK, B_READ_AREA | B_WRITE_AREA);
if (allocationArea < B_OK) {
@ -1720,6 +1723,13 @@ heap_debug_malloc_with_guard_page(size_t size)
return NULL;
}
if (mprotect((void *)((addr_t)address + areaSize - B_PAGE_SIZE),
B_PAGE_SIZE, PROT_NONE) != 0) {
panic("heap: failed to protect guard page: %s\n", strerror(errno));
delete_area(allocationArea);
return NULL;
}
area_allocation_info *info = (area_allocation_info *)address;
info->magic = kAreaAllocationMagic;
info->area = allocationArea;
@ -1731,7 +1741,7 @@ heap_debug_malloc_with_guard_page(size_t size)
// the address is calculated so that the end of the allocation
// is at the end of the usable space of the requested area
address = (void *)((addr_t)address + areaSize - size);
address = (void *)((addr_t)address + areaSize - B_PAGE_SIZE - size);
INFO(("heap: allocated area %ld for guarded allocation of %lu bytes\n",
allocationArea, size));