ARM: KVM: Fix unaligned unmap_range leak (d3840b26) · Commits · 戴 / test

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:

Marc Zyngier <marc.zyngier@arm.com> Signed-off-by:

Christoffer Dall <christoffer.dall@linaro.org>

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;
		}
		}

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