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Kernel: fix memory leak in PageTable 

PageTable used to leak 2 pages on creation and other two on deletion
This commit is contained in:
Bananymous 2023-07-19 23:17:39 +03:00
parent 98cedf155c
commit ba9fa00947
1 changed files with 8 additions and 14 deletions
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22
kernel/arch/x86_64/PageTable.cpp
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@ -140,18 +140,20 @@ namespace Kernel
uint64_t* pml4 = (uint64_t*)P2V(m_highest_paging_struct); uint64_t* pml4 = (uint64_t*)P2V(m_highest_paging_struct);
pml4[pml4e] = V2P(allocate_zeroed_page_aligned_page()); pml4[pml4e] = V2P(allocate_zeroed_page_aligned_page());
pml4[pml4e] = (pml4[pml4e] & PAGE_ADDR_MASK) | (Flags::ReadWrite | Flags::Present); pml4[pml4e] |= Flags::ReadWrite | Flags::Present;
uint64_t* pdpt = (uint64_t*)P2V(pml4[pml4e] & PAGE_ADDR_MASK); uint64_t* pdpt = (uint64_t*)P2V(pml4[pml4e] & PAGE_ADDR_MASK);
for (uint64_t i = 0; pdpte + i < 512; i++) for (uint64_t i = 0; pdpte + i < 512; i++)
{
pdpt[pdpte + i] = V2P(allocate_zeroed_page_aligned_page());
pdpt[pdpte + i] = s_global[i] | (Flags::ReadWrite | Flags::Present); pdpt[pdpte + i] = s_global[i] | (Flags::ReadWrite | Flags::Present);
} }
}
PageTable::~PageTable() PageTable::~PageTable()
{ {
// Verify that kernel memory fits to single page directory pointer table
static_assert(0xFFFFFFFFFFFFFFFF - KERNEL_OFFSET < 4096ull * 512ull * 512ull * 512ull);
constexpr uint64_t kernel_pml4e = (KERNEL_OFFSET >> 39) & 0x1FF;
constexpr uint64_t kernel_pdpte = (KERNEL_OFFSET >> 30) & 0x1FF;
uint64_t* pml4 = (uint64_t*)P2V(m_highest_paging_struct); uint64_t* pml4 = (uint64_t*)P2V(m_highest_paging_struct);
for (uint64_t pml4e = 0; pml4e < 512; pml4e++) for (uint64_t pml4e = 0; pml4e < 512; pml4e++)
{ {
@ -162,21 +164,13 @@ namespace Kernel
{ {
if (!(pdpt[pdpte] & Flags::Present)) if (!(pdpt[pdpte] & Flags::Present))
continue; continue;
if (pml4e >= kernel_pml4e && pdpte >= kernel_pdpte)
break;
uint64_t* pd = (uint64_t*)P2V(pdpt[pdpte] & PAGE_ADDR_MASK); uint64_t* pd = (uint64_t*)P2V(pdpt[pdpte] & PAGE_ADDR_MASK);
for (uint64_t pde = 0; pde < 512; pde++) for (uint64_t pde = 0; pde < 512; pde++)
{ {
if (!(pd[pde] & Flags::Present)) if (!(pd[pde] & Flags::Present))
continue; continue;
vaddr_t vaddr = 0;
vaddr |= pml4e << 39;
vaddr |= pdpte << 30;
vaddr |= pde << 21;
vaddr = canonicalize(vaddr);
if (vaddr >= KERNEL_OFFSET)
return;
kfree((void*)P2V(pd[pde] & PAGE_ADDR_MASK)); kfree((void*)P2V(pd[pde] & PAGE_ADDR_MASK));
} }
kfree(pd); kfree(pd);