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Commit d3840b26 authored by Christoffer Dall's avatar Christoffer Dall
Browse files

ARM: KVM: Fix unaligned unmap_range leak 



The unmap_range function did not properly cover the case when the start
address was not aligned to PMD_SIZE or PUD_SIZE and an entire pte table
or pmd table was cleared, causing us to leak memory when incrementing
the addr.

The fix is to always move onto the next page table entry boundary
instead of adding the full size of the VA range covered by the
corresponding table level entry.

Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
parent 240e99cb

arch/arm/kvm/mmu.c

+7 −7
Original line number Diff line number Diff line
@@ -132,37 +132,37 @@ static void unmap_range(struct kvm *kvm, pgd_t *pgdp, 
	pmd_t *pmd;

	pte_t *pte;

	unsigned long long addr = start, end = start + size;

	u64 range;

	u64 next;



	while (addr < end) {

		pgd = pgdp + pgd_index(addr);

		pud = pud_offset(pgd, addr);

		if (pud_none(*pud)) {

			addr += PUD_SIZE;

			addr = pud_addr_end(addr, end);

			continue;

		}



		pmd = pmd_offset(pud, addr);

		if (pmd_none(*pmd)) {

			addr += PMD_SIZE;

			addr = pmd_addr_end(addr, end);

			continue;

		}



		pte = pte_offset_kernel(pmd, addr);

		clear_pte_entry(kvm, pte, addr);

		range = PAGE_SIZE;

		next = addr + PAGE_SIZE;



		/* If we emptied the pte, walk back up the ladder */

		if (pte_empty(pte)) {

			clear_pmd_entry(kvm, pmd, addr);

			range = PMD_SIZE;

			next = pmd_addr_end(addr, end);

			if (pmd_empty(pmd)) {

				clear_pud_entry(kvm, pud, addr);

				range = PUD_SIZE;

				next = pud_addr_end(addr, end);

			}

		}



		addr += range;

		addr = next;

	}

}