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UnmapPages(): Avoid potential integer overflow.

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git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@37192 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Ingo Weinhold 2010-06-21 14:28:07 +00:00
parent 8bcc0694ad
commit 86b6de1fae
1 changed files with 8 additions and 9 deletions
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17
src/system/kernel/arch/x86/paging/32bit/X86VMTranslationMap32Bit.cpp
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@ -332,26 +332,27 @@ void
X86VMTranslationMap32Bit::UnmapPages(VMArea* area, addr_t base, size_t size,
bool updatePageQueue)
{
page_directory_entry* pd = fPagingStructures->pgdir_virt;
if (size == 0)
return;
addr_t start = base;
addr_t end = base + size;
addr_t end = base + size - 1;
TRACE("X86VMTranslationMap32Bit::UnmapPages(%p, %#" B_PRIxADDR ", %#"
B_PRIxADDR ")\n", area, start, end);
page_directory_entry* pd = fPagingStructures->pgdir_virt;
VMAreaMappings queue;
RecursiveLocker locker(fLock);
while (start < end) {
do {
int index = VADDR_TO_PDENT(start);
if ((pd[index] & X86_PDE_PRESENT) == 0) {
// no page table here, move the start up to access the next page
// table
start = ROUNDUP(start + 1, B_PAGE_SIZE * 1024);
if (start == 0)
break;
start = ROUNDUP(start + 1, kPageTableAlignment);
continue;
}
@ -429,9 +430,7 @@ X86VMTranslationMap32Bit::UnmapPages(VMArea* area, addr_t base, size_t size,
Flush();
// flush explicitly, since we directly use the lock
pinner.Unlock();
}
} while (start != 0 && start < end);
// TODO: As in UnmapPage() we can lose page dirty flags here. ATM it's not
// really critical here, as in all cases this method is used, the unmapped