Commit bbeb3406 authored by Huang Ying's avatar Huang Ying Committed by Avi Kivity
Browse files

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: default avatarAvi Kivity <avi@redhat.com>
Signed-off-by: default avatarHuang Ying <ying.huang@intel.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 6c3f6041

mm/memory-failure.c

+3 −0
Original line number Diff line number Diff line
@@ -1298,6 +1298,9 @@ done: 
	return ret;

}



/*

 * The caller must hold current->mm->mmap_sem in read mode.

 */

int is_hwpoison_address(unsigned long addr)

{

	pgd_t *pgdp;

virt/kvm/kvm_main.c

+2 −1
Original line number Diff line number Diff line
@@ -947,12 +947,13 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr) 
	if (unlikely(npages != 1)) {

		struct vm_area_struct *vma;



		down_read(&current->mm->mmap_sem);

		if (is_hwpoison_address(addr)) {

			up_read(&current->mm->mmap_sem);

			get_page(hwpoison_page);

			return page_to_pfn(hwpoison_page);

		}



		down_read(&current->mm->mmap_sem);

		vma = find_vma(current->mm, addr);



		if (vma == NULL || addr < vma->vm_start ||

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