KVM: Fix a race condition for usage of is_hwpoison_address()
is_hwpoison_address accesses the page table, so the caller must hold current->mm->mmap_sem in read mode. So fix its usage in hva_to_pfn of kvm accordingly. Comment is_hwpoison_address to remind other users. Reported-by: Avi Kivity <avi@redhat.com> Signed-off-by: Huang Ying <ying.huang@intel.com> Signed-off-by: Avi Kivity <avi@redhat.com>
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@ -1298,6 +1298,9 @@ done:
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return ret;
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}
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/*
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* The caller must hold current->mm->mmap_sem in read mode.
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*/
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int is_hwpoison_address(unsigned long addr)
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{
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pgd_t *pgdp;
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@ -947,12 +947,13 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr)
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if (unlikely(npages != 1)) {
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struct vm_area_struct *vma;
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down_read(¤t->mm->mmap_sem);
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if (is_hwpoison_address(addr)) {
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up_read(¤t->mm->mmap_sem);
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get_page(hwpoison_page);
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return page_to_pfn(hwpoison_page);
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}
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down_read(¤t->mm->mmap_sem);
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vma = find_vma(current->mm, addr);
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if (vma == NULL || addr < vma->vm_start ||
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